diff --git a/Project.toml b/Project.toml
index aa147267..128b0e13 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "DistributedFactorGraphs"
 uuid = "b5cc3c7e-6572-11e9-2517-99fb8daf2f04"
-version = "0.15.1"
+version = "0.15.2"
 
 [deps]
 Base64 = "2a0f44e3-6c83-55bd-87e4-b1978d98bd5f"
@@ -46,7 +46,8 @@ GraphPlot = "a2cc645c-3eea-5389-862e-a155d0052231"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 Manifolds = "1cead3c2-87b3-11e9-0ccd-23c62b72b94e"
 Pkg = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
+Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["Test", "GraphPlot", "LinearAlgebra", "Manifolds", "Pkg"]
+test = ["Test", "GraphPlot", "LinearAlgebra", "Manifolds", "Pkg", "Statistics"]
diff --git a/src/FileDFG/services/FileDFG.jl b/src/FileDFG/services/FileDFG.jl
index 4455ed17..5421e6d3 100644
--- a/src/FileDFG/services/FileDFG.jl
+++ b/src/FileDFG/services/FileDFG.jl
@@ -152,6 +152,7 @@ function loadDFG!(dfgLoadInto::AbstractDFG, dst::AbstractString)
     map(f->addFactor!(dfgLoadInto, f), factors)
 
     # Finally, rebuild the CCW's for the factors to completely reinflate them
+    # NOTE CREATES A NEW DFGFactor IF  CCW TYPE CHANGES
     @info "Rebuilding CCW's for the factors..."
     for factor in factors
         rebuildFactorMetadata!(dfgLoadInto, factor)
diff --git a/src/LightDFG/services/LightDFG.jl b/src/LightDFG/services/LightDFG.jl
index cb39cfbe..b4e8b9b9 100644
--- a/src/LightDFG/services/LightDFG.jl
+++ b/src/LightDFG/services/LightDFG.jl
@@ -79,13 +79,13 @@ end
 # end
 
 
-function addFactor!(dfg::LightDFG{<:AbstractParams, <:AbstractDFGVariable, F}, factor::F)::F where F <: AbstractDFGFactor
+function addFactor!(dfg::LightDFG{<:AbstractParams, <:AbstractDFGVariable, F}, factor::F) where F <: AbstractDFGFactor
     if haskey(dfg.g.factors, factor.label)
         error("Factor '$(factor.label)' already exists in the factor graph")
     end
     # TODO
     # @assert FactorGraphs.addFactor!(dfg.g, getVariableOrder(factor), factor)
-    @assert FactorGraphs.addFactor!(dfg.g, factor._variableOrderSymbols, factor)
+    @assert FactorGraphs.addFactor!(dfg.g, Symbol[factor._variableOrderSymbols...], factor)
     return factor
 end
 
diff --git a/src/entities/DFGFactor.jl b/src/entities/DFGFactor.jl
index 83d22b83..3744794f 100644
--- a/src/entities/DFGFactor.jl
+++ b/src/entities/DFGFactor.jl
@@ -38,7 +38,7 @@ Designing (WIP)
 - in DFG.AbstractRelativeMinimize <: FunctorInferenceType
 - in Main.SomeFactor <: AbstractRelativeMinimize
 """
-mutable struct GenericFunctionNodeData{T<:Union{PackedInferenceType, FunctorInferenceType, FactorOperationalMemory}}
+mutable struct GenericFunctionNodeData{T<:Union{<:PackedInferenceType, <:AbstractFactor, <:FactorOperationalMemory}}
     eliminated::Bool
     potentialused::Bool
     edgeIDs::Vector{Int}
@@ -80,7 +80,7 @@ end
 const PackedFunctionNodeData{T} = GenericFunctionNodeData{T} where T <: AbstractPackedFactor
 PackedFunctionNodeData(args...) = PackedFunctionNodeData{typeof(args[4])}(args...)
 
-const FunctionNodeData{T} = GenericFunctionNodeData{T} where T <: Union{AbstractFactor, FactorOperationalMemory}
+const FunctionNodeData{T} = GenericFunctionNodeData{T} where T <: Union{<:AbstractFactor, <:FactorOperationalMemory}
 FunctionNodeData(args...) = FunctionNodeData{typeof(args[4])}(args...)
 
 
diff --git a/src/entities/DFGVariable.jl b/src/entities/DFGVariable.jl
index daae9c60..b11e7474 100644
--- a/src/entities/DFGVariable.jl
+++ b/src/entities/DFGVariable.jl
@@ -226,7 +226,8 @@ abstract type AbstractPointParametricEst end
 Data container to store Parameteric Point Estimate (PPE) for mean and max.
 """
 struct MeanMaxPPE <: AbstractPointParametricEst
-    solveKey::Symbol #repeated because of Sam's request
+    # repeat key value internally (from a design request by Sam)
+    solveKey::Symbol
     suggested::Vector{Float64}
     max::Vector{Float64}
     mean::Vector{Float64}
diff --git a/src/services/AbstractDFG.jl b/src/services/AbstractDFG.jl
index 2812ffce..2f3c8b6b 100644
--- a/src/services/AbstractDFG.jl
+++ b/src/services/AbstractDFG.jl
@@ -76,7 +76,7 @@ getFactorOperationalMemoryType(dfg::AbstractDFG) = getFactorOperationalMemoryTyp
 
 Method must be overloaded by the user for Serialization to work.
 """
-rebuildFactorMetadata!(dfg::AbstractDFG{<:AbstractParams}, factor::AbstractDFGFactor) = error("rebuildFactorMetadata! is not implemented for $(typeof(dfg))")
+rebuildFactorMetadata!(dfg::AbstractDFG{<:AbstractParams}, factor::AbstractDFGFactor, neighbors=[]) = error("rebuildFactorMetadata! is not implemented for $(typeof(dfg))")
 
 ##------------------------------------------------------------------------------
 ## Setters
diff --git a/src/services/CompareUtils.jl b/src/services/CompareUtils.jl
index d4ab0331..9ef53d81 100644
--- a/src/services/CompareUtils.jl
+++ b/src/services/CompareUtils.jl
@@ -43,27 +43,29 @@ end
 """
     $(SIGNATURES)
 
-Compare the all fields of T that are not in `skip` for objects `Al` and `Bl`.
+Compare the all fields of T that are not in `skip` for objects `Al` and `Bl` and returns `::Bool`.
 
 TODO > add to func_ref.md
 """
-function compareFields(Al::T,
-                       Bl::T;
-                       show::Bool=true,
-                       skip::Vector{Symbol}=Symbol[]  )::Bool where {T}
-  for field in fieldnames(T)
+function compareFields( Al::T1,
+                        Bl::T2;
+                        show::Bool=true,
+                        skip::Vector{Symbol}=Symbol[]  ) where {T1,T2}
+  #
+  T1 == T2 ? nothing : @warn("different types in compareFields", T1, T2)
+  for field in fieldnames(T1)
     (field in skip) && continue
     tp = compareField(Al, Bl, field)
-    show && @debug("  $tp : $field")==nothing
+    show && @debug("  $tp : $field") === nothing
     !tp && return false
   end
   return true
 end
 
-function compareFields(Al::T,
-                       Bl::T;
-                       show::Bool=true,
-                       skip::Vector{Symbol}=Symbol[]  )::Bool where {T <: Union{Number, AbstractString}}
+function compareFields( Al::T,
+                        Bl::T;
+                        show::Bool=true,
+                        skip::Vector{Symbol}=Symbol[]  )::Bool where {T <: Union{Number, AbstractString}}
   #
   return Al == Bl
 end
@@ -130,12 +132,15 @@ function compareAll(Al::T,
   return true
 end
 
-function compareAll(Al::T, Bl::T; show::Bool=true, skip::Vector{Symbol}=Symbol[]) where T
-  @debug "Comparing types $T:"
+function compareAll(Al::T1, Bl::T2; show::Bool=true, skip::Vector{Symbol}=Symbol[]) where {T1,T2}
+  @debug "Comparing types $T1, $T2"
+  if T1 != T2
+    @warn "Types are different" T1 T2
+  end
   # @debug "  Al = $Al"
   # @debug "  Bl = $Bl"
   !compareFields(Al, Bl, show=show, skip=skip) && return false
-  for field in fieldnames(T)
+  for field in fieldnames(T1)
     field in skip && continue
     @debug("  Checking field: $field")
     (!isdefined(Al, field) && !isdefined(Al, field)) && return true
@@ -202,10 +207,11 @@ function compareAllSpecial(A::T1,
                            skip=Symbol[],
                            show::Bool=true) where {T1 <: GenericFunctionNodeData, T2 <: GenericFunctionNodeData}
   if T1 != T2
-    return false
-  else
-    return compareAll(A, B, skip=skip, show=show)
+    @warn "compareAllSpecial is comparing different types" T1 T2
+    # return false
+  # else
   end
+  return compareAll(A, B, skip=skip, show=show)
 end
 
 
@@ -236,17 +242,20 @@ function compareFactor(A::DFGFactor,
                        skipsamples::Bool=true,
                        skipcompute::Bool=true  )
   #
-  skip_ = 
-  TP =  compareAll(A, B, skip=union([:attributes;:solverData;:_variableOrderSymbols;:_gradients],skip), show=show)
-  # TP = TP & compareAll(A.attributes, B.attributes, skip=[:data;], show=show)
+  skip_ = union([:attributes;:solverData;:_variableOrderSymbols;:_gradients],skip)
+  TP =  compareAll(A, B, skip=skip_, show=show)
+  @debug "compareFactor 1/5" TP
   TP = TP & compareAllSpecial(getSolverData(A), getSolverData(B), skip=union([:fnc;:_gradients], skip), show=show)
-  if :fnc in skip
+  @debug "compareFactor 2/5" TP
+  if !TP || :fnc in skip
     return TP
   end
   TP = TP & compareAllSpecial(getSolverData(A).fnc, getSolverData(B).fnc, skip=union([:cpt;:measurement;:params;:varidx;:threadmodel;:_gradients], skip), show=show)
+  @debug "compareFactor 3/5" TP
   if !(:measurement in skip)
-  TP = TP & (skipsamples || compareAll(getSolverData(A).fnc.measurement, getSolverData(B).fnc.measurement, show=show, skip=skip))
+    TP = TP & (skipsamples || compareAll(getSolverData(A).fnc.measurement, getSolverData(B).fnc.measurement, show=show, skip=skip))
   end
+  @debug "compareFactor 4/5" TP
   if !(:params in skip)
     TP = TP & (skipcompute || compareAll(getSolverData(A).fnc.params, getSolverData(B).fnc.params, show=show, skip=skip))
   end
diff --git a/src/services/Serialization.jl b/src/services/Serialization.jl
index ba533021..f35b7b5b 100644
--- a/src/services/Serialization.jl
+++ b/src/services/Serialization.jl
@@ -373,14 +373,14 @@ function unpackFactor(dfg::G, packedProps::Dict{String, Any})::DFGFactor where G
 
     # Rebuild DFGFactor
     #TODO use constuctor to create factor
-    factor = DFGFactor(Symbol(label),
-                       timestamp,
-                       nstime,
-                       Set(tags),
-                       fullFactorData,
-                       solvable,
-                       Tuple(_variableOrderSymbols))
-
+    factor = DFGFactor( Symbol(label),
+                        timestamp,
+                        nstime,
+                        Set(tags),
+                        fullFactorData,
+                        solvable,
+                        Tuple(_variableOrderSymbols))
+    #
 
     # Note, once inserted, you still need to call rebuildFactorMetadata!
     return factor