Braces time!!

Hi there,
My eldest daughter needs braces as her mouth is tiny and there are several impacted teeth trying to come down. The dentist advised to see an orthodontist ASAP before it starts to cause her pain and infections.
Money, money, money....
A little bit of a back story, I have 2 children from a previous relationship and the break up 6 years ago was messy to say the least. He has them 3 nights per fortnight and my husband and I have them 11. He earns $15000 per year and doesn't pay child support (he is also self employed). He owns a property which he rents to his parents while he lives in a friends granny flat. He owns a motorbike and a car and the kids come home every ft talking about all the gadgets, video games, drones and other expensive items that he has. So I highly doubt he is legit earning 15k a year.

I asked him for money a few years ago for the children to attend after school activities and it ended in him abusing me and cautioning me to NEVER ask him for money again. So I didn't. And my amazing husband provides for us and our new baby 100% while I am on maternity leave.

Now that my daughter needs some very expensive dental work, I have decided to approach her father for some help financially. He has ignored my text, as per usual.

What can I do?? Can I apply to the family court to look further into his ability to pay child support and other expenses?? What if he counter sues for 50/50?? Should I just allow my hard working husband to fork out thousands of dollars for another mans child? Which he would in a second because he loves and adores them as his own.

4 years ago when I applied to the court to settle a property matter with my ex, he counter sued for 100% custody of the children even though he hadn't seen or spoken to them in 18 months. He ended up with our current arrangement but now the children are both in school I'm worried he will apply for full or 50/50 custody if I push him for money, so I'm very reluctant and scared.