I am curious how some of you feel about that and especially if you are a dive shop owner have you had this brought to you by customer.
I've taught partners who were both getting certified at the same time and that generally hasn't created any big issues. Sometimes you need to split them up because one partner is much better than the other and/or dominating, which can inhibit the other one's learning ... but other than that it's not a big deal. I've seen one case (when I was a DM) of someone who nearly literally dragged his girlfriend into diving classes but she didn't want it. She lasted one lesson. These things do happen but they're not overly common.
I've also had a few cases of certified partners going with their SO's and particularly parents with their children. With this I've had mixed results. Most of the time it's completely ok but you have to be careful to make sure everyone is clear beforehand who is in charge, especially if things go wrong. On the whole I like this if it fits logistically becuase these people will be diving together after the course so it's a good opportunity to get them on the same page.... especially parents with children that they will need to "supervise".
There was only one time that I really had a problem. A guy brought his wife in for a refresher course because they were going on vacation. He was an active local diver but she only dove on vacations. During the pool session something happend (I don't recall what) and he literally pushed me out of the way and took it into his own hands.
I .... ejected .... him from the pool.
Things like this are rare, though, in my experience, so generally I'm quite open to partners or parents who want to be involved.
R..