They could be amended ... but if there is anything audit-able on the tax return, the client may want to leave it alone.  Maybe I'm wrong, but scenario seems like a time where the IRS is going to look closer at the tax return.

What is SUPPOSED to happen is that the clients tell the Marketplace that the child will not be a dependent and then the Marketplace splits things up and sends separate 1095-As.  But the rarely happens, and I *THINK* the Marketplace may be behind that problem.