This is all speculation on my part:
I tend to believe HB was MF’s only friend. We’ve had CN & a guy that worked with MF speak out. No gal pals are defending or criticizing MF.
HB’s friend stated MF announced her pregnancy at dinner immediately after HB announced her own. I doubt MF hatched her plan in a matter of seconds but that she was in a crisis.....CG had already split up & Imo asked her to relocate. I feel MF had been entertaining ideas to get CG to reconsider their relationship & MF had already thought about using the pregnancy tactic. So.....she went with it. Maybe thinking she’d buy time, then miscarry, only time got away, CG didn’t reunite, as far as we know his opinion of their status changed none. MF likely clung to HB during the May-November time frame to be able to mimic Heidi’s pregnancy & get the ever so necessary appointment cards from Heidi’s doctor, to further convince CG she was pregnant. I think MF didn’t so much want Heidi’s baby, any baby would do. But she never had the opportunity to snatch one, leaving only Heidi’s baby. MF was up a creek w/o the proverbial paddle. She wasn’t going to fess up to CG, so she took her plan to the nth degree, going after her best & maybe only friend’s child, hoping Shane would take the fall. Her plan wasn’t well thought out as most of these cases are not. A child with no certificate of birth is a huge problem. Idk if all pediatrician offices are the same but here they request a BC for all new patients. Then there’s the fact that Margo is a Caucasian baby, CG appears to be non Caucasian, at some point I think he would have questioned paternity, etc.
And finally, HB is rotting in MF’s car.
(I don’t actually believe MF wanted a baby as much as she wanted to maintain her housing & get back with CG.