Argh! Sorry for the slow reply. The email telling me about this post got buried in spam.
Unfortunately I'm not sure I understand your question.
It sounds like you want one form to update another. In that case, one of the forms needs a reference to the other. You can either:
1. Give the calculator form a reference to the calling form and have the calculator update the calling form, or:
2. Make the calling form look at the values on the calculator form after that form hides and then update itself accordingly.
I thin the second approach usually makes it easier to understand what's happening.
If I've missed the point of your question, please give some additional detail.
Sorry again about the terribly slow reply.