I understand what OP is trying to do. The kids don't want the direct interaction, however they will be present (it's not like they aren't on the trip with mom&dad). They will have the "memory" of seeing the characters, seeing mom or dad meet the character and get the autograph for them. Meanwhile, the child stands back (next to the picture-taking parent) to watch and avoid direct interaction.
My DD does not have an ASD diagnosis but has many similiarities. It's how their brains are wired, she just loves photo albums and discussing who/what/where/when about each picture, whether or not she was directly involved.
Good luck to OP. Yes, adults may stand in line and get autographs and pictures taken with characters. If you point out your children, the characters will wave to them and not force them to participate. Enjoy your vacation!
Exactly. Just because the kids don't want to risk being touched by the characters, and feel somewhat overwhelmed by direct interaction, doesn't mean that the indirect interaction/observation isn't just as enjoyable for them. They may love the characters and love seeing how the characters interact with people - just not them. If they can be a part of the experience by being there, but not have the pressure/fear of having to go up to the character, they can have a fond memory of it. And enjoy reliving that memory. I understand completely because my son is sometimes the same way. He was afraid of the animals at the petting zoo part in AK...but he didn't want to leave, he just wanted to see away from them and watch.
I didn't really like the character meals. They were loud and a bit stressful. You were always waiting for the characters to come over, and worried about leaving the table etc. The kids didn't eat. My son, 4, ended up LOVING characters. He adores them so much. (I was relieved and shocked). But, he didn't always want to see them at the restaurants. We took his stroller into all the restaurants and he stayed in it, so if he wanted to get out and interact he could. But he doesn't really eat, so that might not work for other kids.
When we first got to WDW, we'd stand and watch the characters from the sideline (many are outdoors, so you can see the people waiting in the queue and the characters). Then as he watched them (and imitated them, as he likes to do), he got comfortable enough to go in line and meet them. Sometimes it took awhile...but as long as he was enjoying watching, that's what we did.
I wouldn't bother with the meals. Find some characters outside and watch the interactions, then if the kids want to do it, great. Another spot to watch Mickey is at Hollywood Studios. You can see him from outside the line. You can also get fastpasses for Mickey at the Theater in Magic Kingdom.
Good luck. Enjoy your trip, and I'm sure you'll be able to get them the autographs and pictures for the photo album. Maybe they would like some pictures of Mom and Dad with the characters!