OOB Play- Legal or Not???

[BOBBYMO]

Yesterday in a (NCAAW)D-1 game there was a out of bounds play on the baseline. The O team ran a stack play and locked arms so that the D could not line up between them prior to the ball being thrown in.

Is this legal or does the D have the right to line up between them if they want to?

After a quick search in the rule book I could not see anything that said either way if the D had the right to line up to defend where ever they wanted.

This is a play that I have not ever seen or heard of.... Whats your opinion???

Legal or not???