Here are several examples of recipes I have found. I have tested but doesnt work.
I keep seeing where 39 pet did not use a previous 34 spell as the combine recipe, 44 uses 39 and 49 uses 44.
Example 1:
http://magecompendium.com/research-library.html
Example 2:
http://web.cecs.pdx.edu/~guardian/res-mag.html
Example 3:
http://forum.magecompendium.com/towe...pic.php?t=3307
Not sure if this helps any at all or not.