Call In The Family?

In any failed relationship there are two sides to the story. When my first marriage failed my parents were instant on my moving back home. There I went with two kids in tow. I appreciated it then and to this day still do. I didn't tell my parents all the details of the marriage because I -#1 didn't want my father to do injury to the father of my children and I felt I was old enough to handle my own problems. He pulled some pretty nasty crap after I moved back home and I often wondered why my father didn't go nuts on him. Instead he kept his cool and later I realized that he did so to not badmouth him in front of his children. Believe me, he voices his opinion now.
We have a similar situation now. My daughter has moved back home. She shares custody of the twins. I have tried to remain neutral in the situation siting the "two sides to every story" theme. He's pulled some crap like loosing their tax return to a student loan he swore he paid off, not telling her about the state refund (swearing it never went in the account) and promising her money and having some bullshit excuse when he can't pay her. Problem is he likes to spend money. He likes to go to Cigar bars and buy expensive booze. The final straw came this weekend. In lieu of some money she had borrowed him last year he made the agreement to continue to cover her car insurance for 1 year. On Saturday she found out he hasn't paid it in 6 months. 6 months she's been driving around with her kids and no insurance. To some people this is no big deal but to me it is. Her car is parked now until her doctor releases her to drive but we are now in the scramble to insure her car. But of course there is a road block as Mr. Responsible cannot locate the title so we can have his name removed, switch it to our name and insure her car (much cheaper rate) which now means a mess at the DMV. Not my favorite place to go but it is what it is. My problem is having the will power to not open my mouth in front of the kids, so I found my latest release is working outside. This could be a long summer and I could have a beautifully landscaped yard when all is said and done. I think it might be less stress on me to call in the family. Ooops, did I say that out loud.