Apologies if there are typos, my hands are still shaking...
Up until today I used a wee ride front seat for DS. However, this wasn't ideal as my knees kept hitting it and DS was getting too wriggly. So picked up a Hamax Siesta this weekend and have just fitted it. And well. Fucking hell. The bike started fish tailing straight off and I only just stayed upright, and we turned around and hadn't to walk home 

So. Any tips on using a rear seat safely please?!