suggest you don't open "many" subforms. there's a lot of overhead when you
open multiple subforms in a single main form. since you're using a tab
control, your users will only be able to see one subform at a time anyway;
so you can use *one* subform control, put it on the main form "behind" the
subform and it will show up on all the tabs. then use some code to load the
appropriate source object to the single subform control, depending on which
tab is clicked.
hth