This situation sounds complicated enough to really need a professional involved, an M.D. or Ph.D. that specializes in the dynamics of families with autistic-spectrum disorders. The worst-case scenario is that the older child could cause severe harm or potentially death to either or both of the small boys (that would certainly be worse than foster care).

Harm in what way and for what reason?

Considering ASD is the diagnosis of the older boy, the younger boys have jostled his routine. I would also think they cause more noise which may hurt his senses.

If by harm you mean hit or push, then the teen likely has fight as his first response. There are therapies available that would help him process this change to his home life in a more positive way.

Most people on the spectrum (just like people with any disability) are more likely to become victims of violence than to cause violence.

Perhaps you could offer to take the older boy to special play dates with an Autism club or group. The most effective solution would be to have enough supervision so that they aren’t left alone together.

My heart goes out to you in this situation. Tread carefully. Even consulting a social worker or child psychologist in the area might end up having unintended consequences where child protective services services gets into the loop and often makes a bad situation far worse.

I hate to be the bad guy here but depending on what “harming” means, there really ARE worse things than foster homes.
Would YOU consider being a foster parent to these kids? The state gives a stipend to offset the cost of caring for them.

If he is harming them he should be somewhere else. Perhaps a group home.

A friend whose oldest child is ASD recently harmed his younger siblings and having issues in public school where he was mostly mainstreamed. They transferred him to school for ASD students and he is doing much better in school and at home.

I worked for one day in a home for autistic people after weeks of training. I thought I was prepared, but I wasn’t. Hitting themselves, problems communicating, mood and emotional issues, it’s tough.

I think three children and one with autism is a LOT for one older woman to handle. Like others have said, I’d get a professional involved, or perhaps someone else in the family could step up to help.

I second @hearkat – ASD can have other other behaviors that sometimes specialized schools or programs can help with or he could have another disorder that needs treatment.

The neighbor boy has an Aspergers diagnosis with several other behavioral disorders tossed in and has a long history of harming even older and larger children (and by harming I mean he caused a 3rd grade boy a concussion and stitches whilst he was a kindergartner).
He was sent for inpatient treatment so they could find medications to help his impulse control. I thought it seemed cruel and unusual to have a 5 year old hospitalized in a mental health ward..but the end result was in fact dramatic improvement (once they found meds to help him) in his home life and it’s what keeps his younger sister “safe” and in the home…so I suppose it was the right choice, even if it seemed extreme to those of us looking in from the outside.

So, in short..if you can make a suggestion to the grandmother suggest she confide in the older boy’s pediatrician and ask for help. For the safety of the younger kids and also for the success of this young man’s future life..it would be worthwhile to get him into an ASD school program, counseling and/or seek treatment to help him. He can’t go around harming people smaller than him for long..and so she has to curb this behavior now in order for him to have any future in the general public.

Can the Grandmother get some assistance on a daily basis?
Home Care?
Or separate the older boy ( activities) .
If not then they should be supervised when all together all the time.
If Grandmother cannot do that..then Professional Care should be sought for an equitible solution, for all their saft needs first.