"Only" half siblings?
Half siblings can be as close or closer than full siblings. Especially if they grew up in the same house (as it appears that Maggie and Beth did). Their interaction at the farm indicates that they were close.
And yes, I think they were "only" half siblings. (Full disclosure, I had a half sibling and I object to the term "only").
Yes, Beth and Maggie are close, as demonstrated in:
- Maggie's desperation to save Beth from the suicide attempt
- Beth asking Maggie to join her in suicide (no one would ask an estranged person to do that)
- Maggie's frantic screaming upon discovering Beth was not on the bus escaping the Governor's 2nd attack.
- Maggie's voice over asking Daryl about Beth's fate.