2 "lookup" forms sharing the same lookup field - how to?

2 "lookup" forms sharing the same lookup field - how to?

Hi,
I have one main form asking for someone's age and I want to access 2 other 'lookup' forms based on the age entered.  Each of these other 2 forms (one to do with nutrition and the other to do with exercise) are designed to be looked up based on age.  I don't want to combine these 2 forms (for a bunch of reasons) but how can I access both of them in the main form without the user having to enter their age twice on the main form?
I was thinking I would have the 2 age lookup fields in the main form but try to hide the second one and in a deluge script assign to the second one the value entered into the first one - but I can't find how I would do that in deluge.
thanks
Janek