Thanks Wagtail.
The daughter got tagged by a hoof perhaps meant for the other mare and she wanted to sell her. I told her first we need to see if Silver can be a 'learning' experience.
In the process we are learning how to lead them. I think we may wait until spring to start working with a cart and wagon. The colt and filly are starting to become real pets. We have a German Sheppard/Lab mix and even the colt and filly have the bluff on her.
I never knew horses of any size were high volume fertilizer plants.
Good stuff Mate & you are very right about your daughter, and family, needing this to be a 'learning experience'. It is and there are many books on the subject. Your family are going to have to learn the nature of horses... how to be around them, interact with them and, eventually, train them.
You might look up Tom Dorrance (book: True Unity, pub 1987), in it, he talks about his response to the riders who came to him because they thought they had a horse problem. He summed it up in the phrase,'I tell them that the horse is having a "people-problem".' In other words, as far as the human is concerned, the horse may not be doing the right thing - but as far as the horse is concerned he/she always is, for self-preservation is his/her inevitable motivation. (I'm paraphrasing another author - Mary Wanless: For the Good of the Horse, pub 1997) [a VERY good book]
Other knowledgeable people to research are; Ray Hunt, John Lyons, Pat Parelli and (my favourite) Monty Roberts. You'll need to learn 'Equus' - The language of training... Probably as yet another home schooling subject.

It really is 'magic' when you and your horses start to communicate, both on the ground and in the saddle (or driving them with a cart).
As to the production of manure... that seems to me to be their primary function. And they're darn good at it! :laughing: I try to pile it up for future garden/pasture use, but sometimes I just hop on my tractor and chain-harrow the droppings in place IOT future improve the paddock.