[AUCTeX] TeX-auto-save and files with the same basename

[Vladimir]

Hello all!

I'm using AUCTeX and find it very convenient. But I don't know how to 
solve the following problem:
I edit a file which has a supplementary file with the same basenames 
(for example, revtex4 uses <basename>.rty as supplementary file for 
every <basename>.tex file) so AUCTeX generates (I set TeX-auto-save to 
't') 'el' files for such files and they override each other, of course. 
I thought that there is a variable (file variable?) which tells what 
'el' file will be generated (in case if basename of several files 
coincide) but did not find any.

Now I do following:
first, save (regenerate 'el' file) supplementary file then rename it
second, save (regenerate 'el' file) main (tex) file and add to that file 
content of first generated one (not verbatim, of course).
This works OK, but when I'm changing something in supplementary file the 
'el' file is overridden, and I do the same procedures.

Any suggestions?

May be it is worth to construct 'el' file name not only on base of 
editing file basename? For example, if tex file has a name
thesis.tex
and supplementary file has name
thesis.rty
then corresponding 'el' files would be
'thesis-tex.el' and 'thesis-rty.el'.

P.S. Sorry, if my English is poor.

---
WBR, Vladimir Lomov