I have first hand knowledge of how Sheila must have felt,,because when I married ( years ago ) I took on two children from a previous marriage where the mother had simply abandoned them. The mother had signed a document for the court saying that she didn't want the children,or anything to do with them. That said,,neither child ever received a Birthday nor a Christmas card from her.
The boy didn't appear to be affected,,and wasn't so during his school years or adult years,,but the girl was deeply affected by this abandonment.
I didn't take over a mother-role,nor act as a surrogate,instead,more a big sister who was looking after them.
The children were well-behaved,well-mannered and a treat to take anywhere and my mother took them on as her " grandchildren " as they used to stay with her,and she enjoyed having them.
However,as time went on,,the girl started showing signs of violence,mistrust and a hatred towards her father,,for no reason. Because I realised that the girl,,in her teens,,wasn't well,,I made an appointment at the GP's,who in turn referred me to a psychiatrist,,and lo and behold,,,it was to do with the fact that her mother no longer wanted her,and she was blaming her father for not doing enough to " bring her back " .
Daughter had a spell in a clinic,,and was so violent through frustration and not because she was a violent child. Poor soul was drugged up to the hilt. We went through a terrible time,and she appeared to have changed,,it was awful. This is why I felt so much for Sheila,and wished I'd been there for her.
Like Sheila,,daughter started mixing with the wrong people,,out of revenge,I think and as a form of rebellion, to be noticed.
I had two daughters of my own,but didn't treat them any differently from the other two children,who were delighted anyway with their two little sisters.
It was certainly a battle over the years,,but we were a family and all stuck together no matter what,,but poor elder daughter did suffer with her demons,for years and periodically had spells in the clinic when she felt that she couldn't cope.
This daughter rings me every week,,,my own flesh and blood dont.

PS,,and yes,daughter did attempt suicide as well. We also had rellies that didn't know the half of it. Too busy counting their money !!