Access -how pass a from data to sub form within a tab control?

[kkc]

Hi,
looking forward for your advice, the situation is like this:
i have master form, namely frmMaster.
within the frmMaster there is a tab control with 2 pages,
each page within the tab control has a sub form,
i.e page 1 of tab control have frmSubA and page 2 have frmSubB

when i press a date button in frmSubA, it come out a new form, frmDate, which have a calendar control, when the user click a date in the calendar control, i want to pass the date value back to a textbox control (i.e txtDate) to frmSubA,
How can i do that?