I want to run 2 versions of Excel that communicate with each other.
This seems unusual, but let me explain why:

I have purchased a addin called "Evolver" which I want to run a macro
that runs another addin (that I've also purchased) called "Ptestpro".
"Ptestpro" has a menu that it adds to Excel.

The problem is that Excel does not seem to allow this. One addin
cannot run another addin, not even by sending keystrokes (using
"sendkeys") to the menu of the other addin.

So the only solutions I can think of a
1. copy all the code of "Ptestpro" to a spreadsheet that is being
processed by "Evolver". (I am unclear as to whether this would help)
2. Run two instances of Excel, one of which has the "Evolver" addin,
the other which has the "PtestPro" addin. Evolver in one instance
would send a message to run "Ptestpro" in the other instance. When
"Ptestpro" is done, Ptestpro writes an answer to a cell in its instance
of Excel. This answer would have to be retrieved somehow by the Excel
running "Evolver".
so this breaks down to three parts:
a) Excel1 runs a macro in Excel2
b) Excel1 waits for Excel2 to finish running the macro
b) Excel 1 retrieves a value from a cell in Excel2

My question is, is this the way to go, and if so, what the code look
like?

Or is this a too complicated way of solving this problem?
Thanks,
HA