Okay,
This isn't normal bad behavior. These children have probably been neglected/abused, then they have been uprooted completely from everything they knew, then as they settled down again, they get uprooted again! And again, if they had more than one FC. Your friends children are not like other children! They are traumatised, they are scared, they are probably angry, and don't trust adults. You cannot know how these children behave for her, or for their grandparents for that matter. The children you see are probably different from the children that your friend has 24/7, or the grandparents see if they were spending more time with them.
Sadly, family can't be made to be supprtive. A member of my family was not supprtive, and we broke contact. Your friend must be in a rough place right now, poor thing, but she can't make her family be supportive, sadly. I think you have done the right thing offering to help. I would offer to pick up the kids, and I would also offer to be a listening ear for her whenever. I know she may feel like it is taking advantage, but I would still make it clear the offer is there.
I would also direct her to AdoptionUK if she isn't there already, they have a message board full of parents who have been in her situation, and come through. Lack of support and a very difficult first few months are so common. They can advise her, and there is also a helpline available to ring for support.
SS should be offering some support, especially if she isn't coping, though, sadly, some LA's are seriously lacking in this. Also, of your friend seems depressed, she can speak to her GP. Post adoption depression happens.
I have bumped a thread started by a friend in aa similar position - trying to support her friend, with children recently placed
Make it clear that YOU are supporting her!! You can be a listening ear or her, and some help with the kids if need be. Make it clear she is not alone, and direct her towards services (especially AdoptionUK and messgae boards there - and of course she's welcome here as well!)
To alwaysleftout, adoption disruption is tragic, but frankly happens a lot because there is not enough support given! Jeez, if childcare and a bit of 'bad behavior' were the only issues, then it would be a walk in the flaming park!! What do you do if your new child is rejecting you constantly, swearing at you, hitting you, leaving you covered in bruises? You ask for help and don't get any. You don't have a parent-child attachment yet because you only met them a couple of months ago. Your child certainly doesn't love you, and your life becomes a living hell very quickly! Is it any wonder disruption happens? Parents can't cope any more. And yes, birth parents who can't cope CAN place their child in care! They do!