Subfile Entry Pgm

Help; I've written a subfile where I initialized 300 records SFLSIZ = 300
and SFLPAG = 15. The user enters one field and field exits to the next
subfile line. The problem is when they get to the bottom of the page line 15
if they do not use the roll down field to the next page,  they will write
over the 1st subfile record on the existing page. What I like to do is a
force control back to the program on the last field exit of the page.
Problem SFLENTER does not allow indicator options. Anyone got a an idea?
        Thanks
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