Need to change return to different location
 

I purchased a RT ticket from RSW-BOS non-stop for our son to meet us in Florida during school break. He just found out that he was accepted to grad school in Atl and will need to be there the day he was scheduled to depart from RSW to BOS. If he is booked on another flight the same day from RSW-ATL will we risk a flight being cancelled?

Yes.

It may cancel one or both. DL may call and ask which one, but then again, it may not.

Either book the RSW-ATL on WN or cancel the BOS ticket. Depending on its cost and presuming a $200 change fee, it may be feasible to cancel the BOS ticket and purchase the RSW ticket with those funds.

Have to do the research.

OP might also consider taking RSW-BOS as ticketed, and BOS-ATL immediately thereafter on a separate ticket

another option might be a Same-Day-Confirmed change to RSW-ATL-BOS and skip the ATL-BOS leg
> $75 for a non-status passenger
> not an option for a Basic Economy ticket
> would require same inventory for a coach ticket, but only an available seat for eaither Comfort+ or First Class
> would not work with checked baggage
> yes I know hidden-city is illegal and unethical, but on a one-time basis it might be worth the risk

If I understand right, you have a BOS-RSW RT (NOT RSW-BOS, which would mean RSW-BOS//BOS-RSW with Boston as the destination) and now son needs to fly BOS-RSW and then RSW-ATL. Will he then fly ATL-BOS at the end of the same day or a day or two later? Or is he essentially moving from BOS to ATL by way of RSW? And is there any arrangement for the grad school to at least partially reimburse his travel? If so, what are the rules?

It might help to know for sure that the change fee on the ticket is $200 as folks here are assuming, so that it's a nonrefundable ticket but not basic economy (and not an award ticket either). If so, the question is whether you can do better than simply paying the change fee to replace RSW-BOS by RSW-ATL, which I suspect won't be considered an open jaw because of the distances. (The unflown portion can't be longer than the flown segments.) If it's an E ticket, you have no option at all to change it and the only choice is whether to buy RSW-ATL or BOS-ATL.

Book the new flight on a different airline and keep the current one as is in case of schedule change or IROPS for a refund or credit.

I must just live dangerously, I’ve don’t this several times without having a problem.