Hi
I think you could be a great source of love ,builder of sel esteem and just being someone who loves him for who he is
.Like you would for any other Grandchildren you may have.My one Granddaughter has ADHD, behaviour disruptive disorder ,plus ,on autism spectrum.She has had excellent therapy since age 4 ,and continuing therapy.Plus managed by a Psychiatrist and Pediatrician .The Mom has therapy to know how to manage her behaviour.
We as Grandparents are informed by our Daughter of what she’s doing with therapy
But no one knew why she cried when her Mom left for a few hours and couldn’t handle the separation like her Sister did,or why she would be very angry at her sister fighting ferouciously and repetitive calling out of same sentence again and again.
I know now to change up as soon as possible the situation or else it becomes a problem situation where someone gets hurt.So as soon as I hear the smaller child crying and repeating stop stop .I get into it by changing the scene.Remove the object they’re fighting over ,bring in a nice snack and water ,remove the smaller child to a different chair with a bottle of milk or food or comfort toy
Focus on how the older one is and make her situation happy .
We are here as Grandparents to love unconditionally our Grandchildren.We aren’t there to modify their behaviour or provide the new skills the parents are trying to teach her .So just be a loving Grandparent.Ask your Daughter about the symptoms and behaviour issues that you should be aware of and how best to handle situations.
Tell her you will be available by cell phone all the time the Grandson is with you.Start with staying at their house while the Mom is home
Then take them out for ice cream and return
Pick them up at school and say Hi to their teachers
It’s amazing how important it is for the Grandchildren to have the support of their teachers as you are being entrusted with their safety to take them home
Then have your Daughter come over with them and have lunch
Take out or what they want.
Be bender of rules eg let’s have ice cream and chips after lunch
Indulge a bit
Make sure to grocery shop the day before they visit so you have everything they like in your easy to open treat cupboards
Special ice cream bars popsicles or watermelon in fridge or freezer
I always have the expensive snacks that sometimes they don’t always get like Pistachios ,sunflower seeds,specialty ice cream snacks etc
My Grandchildren are allowed anything they want in cupboard as soon as they arrive
Everything is what they want
It takes time,Don’t expect too much at first because it takes time to understand and learn about them
Good luck Gramps

My Granddaughter doesn’t like loud noises or bright lights inside the house so when she closes the blinds we leave them closed.
If she is over we try to keep things calm.
Let her take the dog by the lead when we go for a walk.We have taken them many places.Disney cruise was quite an experience.We just adapted it to our needs not the cruise itinerary.So when everyone went to the island we stayed on board and had the ship pool to ourselves.We didn’t bother with photos of the dressed up characters or participate in the little girls dress up make up day.
Who cares !! It’s for your Grandson’s joy
I paid over $600 for the Cirque de Solieil show yet we could only stay 10 minutes because it was too loud and close to our seats
Her well being takes precedence
Explain to your Daughter that this is how you would manage having him over .
On his terms with you as a loving Grandfather
They need confidence.
So just be yourself but ensure you praise his artwork or whatever he’s doing.
We happened upon doing puzzles with her at a young age.We bought her a puzzle table because she loves doing puzzles.They were always on the floor then put back.
So we bought her this table on Amazon and she stands at it during winter or rainy days or whatever and she does 1000 puzzles very well.I buy puzzles of the theme of things she likes eg she loves frogs so got a beautiful bright puzzle of large frog with marine life
It’s now framed in her bedroom
She is in competition with her Grandfather who likes puzzles.He goes over and says things like “Oh yes you are so good at puzzles and are ahead of me “
This causes excitement in her doing puzzles because she’s better than Papa .
So slowly by asking him what he like in animals,colours Activities you will get to know him and then just be there as a supportive loving Grandfather .No judgement .No parenting.Just a Grandpa.