No, no, we're not trying to avoid canon! Heavens no. If we did, there's not much point of doing an Accel World RP in the first place, right? We're talking about the canon storyline
, where Haruyuki, Snow Black, etc. figure into. Having Ash Roller in our story opens up the possibility of meeting with those characters, getting involved in those events.
You should ask daltar about the specifics of the setting, whether we're just another string of events going side by side in the main story or we're going with a full-blown AU.
Another reason to be iffy about Ash Roller is: why would he make you his Child? Something that fits with his personality, because honestly I can't see him siring anyone. I mean, sure, if you can RP him convincingly enough, go for it.
And most of all, if you want Ash Roller in the story, why not as his buddy or something? There's no real reason to be his Child unless you want to interact with the person behind the avatar. ...do you?