Max5, how to retreive collective full path+name automatically?

If I build a standalone collective from my patch, I'm not able to get its full path+name.

In my custom C object :
I'm getting Max5 path with path_getapppath()
I'm getting folder containing mxf with path_getdefault()
I'm getting patch file name with object_attr_getsym(mypatcher, gensym("filepath")) (without path, because we're in collective)
I'm getting patch title with object_attr_getsym(mypatcher, gensym("name"))

(same in patch with equivalents)

If my collective is A.mxf, I would like to get
fullpath/A.mxf

If I rename A.mxf to B.mxf in Finder, then I would like to get
fullpath/B.mxf

I could use path_topotentialname to build the path, but I have to make assumption on the collective name, which I don"t want.

Now, If I have A.mxf and B.mxf in the folder, B is a copy of A,
If I run A, I want path/A.mxf
If I run B, I want path/B.mxf

Does anybody knows how to get this?

Thanks
Chris