C..
Forgive me for the length of this response......
OK - The CPS "party line" is that if the child's biological parents cannot provide a stable, safe, healthy environment then placement with another biological relative or kin/fictive kin is in the child's best interest.
From CPS's point of view they will ask every relative they can find. They are only looking for a yes or a no.
If it's a yes, they do a background check etc and start the process to "certify" the relative.
If it's a no (or the background check isn't passed), they move on to the next relative. If all relatives don't call back, say no or don't pass the background check.... the kids will be placed in a foster home. They will "try" to place them in one home. How many kids, old they are and what their behaviors/needs are will sometimes make that difficult.
There are TONS of reasons why a relative would be unwilling or unable to accept placement. There are TONS of cases where relative placement works out beautifully for everyone involved. It just depends.
However, I have seen many cases where the child(ren) were removed from their parents and placed with a relative. Then they were disrupted again when the relative couldn't/wouldn't continue to care for the kid(s). Mainly.... placement with a relative doesn't always provide the *incentive* that some parents need to get their sh*t together. So the dysfunction continues that has existed for years (in some form or another). Many times the family has either severed or distanced themselves and aren't willing to get pulled back into the drama. Sometimes the relatives are unwilling or unable to commit to keeping the kids away from the relative or adhering to the CPS "rules". Think about how hard it would be when your sister (brother, daughter etc) knocks on your door at 2pm crying, sobbing, because they "just need to see their kids". In addition to caring for the kids you have to "supervise" the relative from making un-granted contact with the kids. Or..... mom/dad go "off the rails" because their kids are with their sister (brother, mom, dad) and they know their kids will be well taken care of, so they have the freedom to continue to do what they want.
Here is the only thing I will caution.
400,540 children are in the U.S. foster care system.
The average amount of time *in the system* is 23.9 months.
53% have been away from home for a year or longer.
52% are reunified with their birth parents.
The problem when relatives say no and then the kid(s) are in care for 23.9 months before the state terminates parental rights is that it's THEN that relatives will come forward and say "we want them back. They can't stay with strangers". But that's not always possible. If a relative has been uninvolved and comes in at the last minute to try and "keep them in the family" the judge may not decide that "family is best". The judge may decide that the family who has spent the last 2 years with the child is where the child should stay.
Again - it depends on the age(s) and behavior(s) of the kid(s).
I can tell you this (and I say this as a loving foster parent who tries hard to support my foster kids' parents on their journey to reunification) that I would do almost anything to avoid putting a kid "in the system". ANY child who is taken away from their parents is going to have repercussions. Even if they are taken from their parents and placed with their grandparents with whom they already have a relationship.
I can also tell you this. CPS gets THOUSANDS of hotline calls each day. I didn't read the initial question, so I'm not sure what the mom is doing. But it's actually REALLY HARD to get your kids taken away. The state doesn't WANT to take kids. It's expensive. It's exhausting. It's not good for anyone. They want to provide in-home services, provide support, point the parents in the right direction to get help. Unless the child is in IMMINENT DANGER and the house is UNSAFE - either from the environment or the behavior of the parents.... the kids won't be taken.
It's a tricky and complex situation and there is no "good" outcome.
Sorry - I went on a rant. To answer your actual question...... NO -she doesn't "have" to take her sister's kids. CPS won't question her reasons either. She just has to be comfortable with them herself.