I Absolutely agree with Heather!
Blessings to you and these Very Special Sweet babies!!
If Zack (?) Seems to be having balance issues, due to his tail...
I'm wondering if surgery, to "Bob" it at the break, wouldn't help with that...
Since cats do use their tails as rudders, to an extent, when running, jumping, etc.
If he has NO control over his tail, that could account for the balance issues, for example, he wants to "Zig" but his tail "Zags"...throws off his natural balance...
Looking at the picture, he looks like he'd be a very good candidate for tail surgery, and he'd still have a very cute little short tail left and if he is anything like my Biscuit, that little stump is held straight up like an exclamation mark!!
It's only a thought, I figured I'd throw out there...
And like Dumine said, whatever degree they're at right now, is the degree it will stay at.
They will only get better as they learn how to work around everything!!
"A Cat must have three different names:
An everyday family name; A particular name;
And the name but the Cat Himself Knows, and will never confess." T.S. Eliot