Bob,

Give your form class a property for OldDataSession. Then in your child form you can do this in the Init;

LPARAMETERS WhateverYouAlreadyHave, pnDataSession
Thisform.OldDataSession = Thisform.DataSessionID
SET DATASESSION TO pnDataSession
...

In the child form's Destroy put this code;

LOCAL lnDS
lcDS = ALLTRIM(STR(Thisform.OldDataSession))
SET DATASESSION TO &lnDS

The orphaned data sessions result NOT from using set datasession but from NOT reseting the data session when you are done.