Hey there,
I'm a 3d designer with Cinema 4d as my exclusive 3d modelling tool. The task in your project details is quite simple and easy.
I can show you how you can merge or combine all those material & polygonal selection tag into one tag as you wished for in your details.
And on top of it, it'll take the least amount of time (approx few minutes or less) & effort to achieve what you're looking for.
: )
[Note: I just tried to replicate your project scenario in my Cinema 4d to confirm and it took less than a minute to do it. By the way, your Cinema 4d seems like it's R25, is it? ]