To be clear on the Max question, of course I don't mean that he will randomly decide to pair them up. I just meant that should he have a reason to, he might feel the need to do something to help them out (like telling Ash some particular likes that May has).
Before I give my three cents on the bold question, I have to wonder why most Advanceshipping writers don't include Norman & Caroline in the stories for the most part. I mean Pokeshiping fics will show how Misty's sisters take to Ash as their sister's girlfriend, just as Pearlshipping fics will show Johanna's reaction to Ash and Dawn.
What do you think Delia's impression of May as a potential daughter-in-law is?
I don't see any reason for her to object, and well it would likely reassure her to know that someone will look over Ash. She might even find it cute to see their similiar appetites.
Conversely, what do you think Norman and Caroline's impressions of Ash as a son-in-law would be? Would they approve of Ash and May as an item?
Caroline's contestshipping feeling would likely fade if she saw more of Ash and May's interaction. Going with the couple comparisons from an earlier portion of the thread, she and Norman would probably see a bit of themselves in them and would definitely support them.