Revert "Revert "Remove check for preventing re-parenting non-spl..."

Revert "Revert "Use new onStartSplitLegacy when starting split f..."

Revert submission 17918609-revert-17779173-startSplitLegacy-OOWPZEFFGI

Reason for revert: Running through TH
Reverted Changes:
I6d81e0584:Revert "Use new onStartSplitLegacy when starting s...
I754bc308f:Revert "Remove check for preventing re-parenting n...

Change-Id: I190cc9bda28c85a675c3bd8edc2ca2bb43ed677c