impossible to bind to 3d sketch?

[raf]

for convenience I realize my assemblies by binding many parts to sketches, which I then assemble in the final axieme.
In some cases I would be comfortable to create 2d/3d hybrid sketches to which to bind my parts. from the point of view of the sketch there is no problem, inventor manages the 3d sketches quite well, the problem arises when I want to use my 2d/3d hybrid sketch as a basis to bind the parts, to that part of the sketch that is 2d I can safely encourage, to that which is 3d no. Is there a reason for this? Is it possible to do what I ask?
I hope to have been clear in the explanation of my problem, possibly just do a test and you understand immediately what I mean!

Thank you!

 

[Peppe]

try to put points/axes/plates on the 3d sketch and bind your parts to these elements. . .

 

[raf]

My ignorance!
I don't need the 3d sketch for my purpose, just work on the 3 floors, because I didn't think about it before...