I'll just share my insight on the family dynamics presented in this case as I have some personal experience here.
I have been with my present husband for 15 years - we got together after I had already raised 3 children who were out and independent by that time.
I grew up in the suburbs, normal middle-class, my Mom and Dad married, both parents always in the home, 2 siblings, all of us educated, working, responsible members of society.
My husband was raised quite differently - single mother, siblings with different fathers, frequent moves, questions of sexual abuse, drugs, government assistance throughout, etc. By the grace of a higher power, he overcame and is now a wonderful, productive family man, and his family has developed over time as well. He has a huge extended family of cousins, aunts, uncles, nieces and nephews.
When we first met, I was astonished at how the minor children of the various family members were passed around, sent to "live" with other family members, for periods of time ranging from months to many years. Many times no obvious reason was given - just "he needs to go live with grandma" "I can't handle her right now so she can live with Auntie for awhile", "they will stay with Cuz till the mother gets on her feet."
My family was not like that! I would never just drop my children off to "live" with anybody else, even family! I endured divorces, a few address changes, demanding job hours, financial difficulties, mostly as a single mother raising 3 kids. Despite all my troubles, the thought NEVER even entered my head to send any or all of my children to "live" with someone else.
Yet - other folks in different cultures are totally okay with that. Think - "It takes a village" and all that. My husband's family would "take in" ANY of the children any time it was needed or requested.
It took me many years to develop an acceptance of this, as I wondered why Johnny was staying at Aunt Margie's house all year when his mother had a perfectly fine home. After awhile, I stopped asking questions. It just is what it is, so to speak.
My culture growing up was completely different that my husband's - and that doesn't make one better than the other, just different.
As far as the psychological ramifications of children going from caretaker to caretaker, I do not know. The children raised in this manner in my husband's family range from college educated, successful adults to drop-outs, drug users and trouble with the law.
Sorry for the rant, but I guess my point is that folks from different cultures raise their children in whatever way they know, from the way they and their parents did.
SY just perpetrated what she knew, and she probably still believes she is a good mother even though all her children are gone, she may have a "slight" drug problem, she is homeless, jobless and there are serious allegations of abuse. It may be exactly what occurred in her own childhood.
Thanks for listening, I do the best I can to keep an open mind towards those who are different than me. That said, there is no excuse for selling your child, if indeed that is what happened here.