Thanks for all the replies but the selling/bullet isn't going to happen sorry:/
No need to be sorry - I hope - just stay safe! I don't like to sound so negative, just that this sounds like a very unsafe situation. I hope this person that's coming to help the horse is also going to help you & your dad too, to learn how to deal with him effectively *& safely*.
I know it's a common practice, but your dad obviously doesn't get how dangerous it is to put a child(rather than an experienced bronc rider who knows & accepts the risks) on a horse that's *likely* to buck, let alone one that's known for it! And no, just putting you back on, with no thought for the reason for the behaviour, doesn't tend to be effective training either. The horse has already been instantly reinforced for his behaviour, by getting rid of you, so the more you do it, the more 'practice' he's getting at it working for him. If you're going to tackle the problem head-on(which I don't advise) by the horse being ridden before he's ready, you'd better all but guarrantee you can ride out those bucks & not come off.
The better, safer way to do it is to train the horse in such a manner that bucking, being headshy, etc, etc is not all that likely for a start. It sounds like the horse hasn't had strong foundations 'built' to be even ready for saddling, let alone having a child aboard. As the horse already has experience with the effectiveness of bucking, I'd ensure whoever was going to train him for you was aware of this, experienced & willing to 'ride out the bucks' should the need arise.