Forms :: Autofill Block

I have 3 tables

1-pr_mst
2-pr_trn
3-hr_mst

Em_code is a common key between theses tables.

on my form table 1 and 2 are the base main tables, due to the relationship, when i enter em_code on table 1 and query it, it shows data on both the table. Its a normal behavior in Master Detail block in forms.

When user enter em_code at form and there is no data found in table 2, obviously it show blank data block related to the table 2 and shows data in table 1 block, now i want an em_code details which stores in the table 3 automatically load in memory and populated in detail block. Is it possible ? and how can i do this.