In my opinion, AM, no, you should NOT have a relationship w/your AH's sponsor. I think this has been said already, but I'll say it again: HIS recovery is HIS. You really and truly need to keep on your own side of the street.
And bear in mind that your AH's sponsor has no more real control over him than you do. My XAH would call his sponsor every afternoon and then start drinking. Having a sponsor is an important part of recovery, but again, ONLY if the A is actually working with the sponsor, not just saying he has one.