Ooh, I didn't see @Royal Chick's post explaining this when I posted.The reason they don't do well together is that the acid from the vinegar may kill some of the good bacteria from the yoghurt, kefir etc.
Now it isn't totally straight forward because many of these good bacteria are able to survive the hydrochloric acid that gets added into the mix to aid digestion, but probably not all, so you may be making the probiotic less effective.
Personally I wouldn't sweat it too much and just try to keep them separate in timing.
I would see what is most effective sitting in the crop overnight and go with that last thing at night if possible.
I have probably got that all wrong so I will let myself out now and go visit my Princesses.
Thank you @RoyalChick!