In order for the skeleton found in FL to be Heather one of two things must be true.
Either:
1. SM or TM or someone went on a sudden road trip sometime after 4am 12/18/13, and before they were watched by LE, and drove from Myrtle Beach to FL to dispose of HE's body in that bag, where 2 to 3 months later nothing but bones and a blanket, inside a dissolving plastic bag with vegetation growing through and inside, would be found.
or
2. SM & TM kept HE's body for 3 weeks until on or around 1/9/14 they drove to FL so SM could participate in the Disney half marathon, and they took HE's body with them to dispose of HE's body in that bag, eluding whatever LE personnel was watching them, where 2 months later nothing but bones and a blanket, inside a dissolving plastic bag with vegetation growing through and inside, would be found.