Group Additivity Values-Missing groups and Various sources

[venoosam]

I am currently working on MMA (Methyl Methacrylate) oxidation mechanism generation. We noticed that RMG is calculating some of the group additivity values from different sources e.g. benson or other quantum calculations which is being problematic and not reflecting a correct thermo properties values. If they did the thermo values from one source would have been right but summation and relying on various sources gave wrong thermo properties and in some cases missing thermo groups. Such as MMA molecule and another isomers of MMA (C5H8O2)