How to Mediate Child Support Modification

My question involves child support in the State of: Texas

My ex and i had a drawn out (not so nice) divorce. we mediated in march of 09, and it was finalized in nov 09. We seperated feb 08.
In texas we were required to mediate, and are required to mediate for changes.

I agreed to giving up a LOT of time with the kids in the summer in order to avoid the 4 whole weeks in summer issue, which was to end after this summer so summer 2013 should return to normal summer visit standards, however the write up doesn't state that so I need to bring ex back to mediation to rehash it and have judge rubber stamp it again.
I'm expecting some fighting over it, as i agreed he was to have 2 visits 2 weeks long each, gave up my weekend during the month visit (Standard) and allowed him to have thursday overnights continue during summer (normally only when school is in session) to get him to break apart the month long visit.

In addition to that fun, I am going to ask his child support is evaluated, but since he's made the same income for 12 years I doubt it would change anything. However he *claimed* during temp orders hearing he'd be moving to my city and getting an apartment which I knew would never happen. He is 35 and lived with his parents until he was 24, and moved back in when we seperated and he was 31 and it's fast approaching 5 years now. His sister is 7 years younger and has NEVER left home even while getting a four year degree. I say this because it's pretty evident to anyone on the outside that he is never going to move out. so he has both of his parents supporting the children and he's using his income to blow on video games and toys.

Until just recently my daycare cost me 1300/mth, and I have to pay it even when he has custody of the children partly because I have to retain their slots, but also partly because I know he won't pick the kids up and tell daycare I agreed etc. I don't really want to put my daycare in the middle of things.

He pays the standard 25% of gross (539/mth) of childsupport to me.
I was also stuck with the house I never wanted (we looked at over 150 houses and this was the only one he was meh on, and I didn't like at all) because he can't afford it and it's worth nearly half what we payed.

Not sure if there is anything I can do legally regarding the house, since I don't want it....still mulling that one over

What I was curious about is if anyone knows for things that my lawyer didn't think to tell me I can ask/get during remediation, and if the fact my ex is being supported by his parents can play any part in childsupport or daycare costs?

I was/is half tempted to tell daycare not to pick my kids up at school on thurs when ex has them, and fridays when ex has them - but I know what'll happen. I am not interested in playing games with him, but I am quite irritated that he can choose not to pay half a dental bill because it'll cost me more to take him to court over it, or wait 6 months to bother paying for something, or not pay child support for nearly a year and the judge just shrugs....etc.

I'd honestly just have his support order increased and i'll pay 100% of daycare and medical since he doesn't anyway. *sigh*

....and i'll fully admit i'm wavering on angry mom syndrome, just so frustrating that he walks all over me constantly regarding support and visitation and then does stuff to hurt me by hurting my children, and there isn't a thing I can do about it. I generally have to have some snarky fantasy every few months and tell my mom or sister about it just to vent and feel better and keep standing under the pile.
My support order is fairly open to interp however in a lot of situations (like the summer order) and i'm not going to pay a lawyer tons of money to screw things up again, so i'd love advice on getting a better wording going forward, and asking for stuff I might legally be able to get.

what I need is an ironclad, bouncyballs to the wall custody order example. lol!

If this is about child support, what you can expect is that his income will be reviewed and, if changed, the amount may be modified consistent with that change. The same applies to his share of child care and medical expenses.

The terms of the property settlement aren't going to be renegotiated.

My ex has had the same job for over 12 years with almost no raise (he hit the salary cap 9 years ago). his company hires kids out of trade/college and pays them very little and expects them to leave after 6-12m. he complained endlessly entire time we were together, but couldn't be bothered to do anything about it. thats kinda his thing....blame everyone else for problems.

I can show that his field should be paying 50K for 1-2yrs exp, and 60k for 2-5.
obviously his <30k a year salary is below his earning potential, esp since he has a degree.

not to mention his free cost of living situation etc.

Does anyone know if texas will even consider this? so far my exp with texas court systems seems terribly biased towards the man :(