Texas Child Custody Help

I am a divorced mother of 4 kids who were in my custody until June of this year. The kids are in the temporary custody of their father pending final hearing in October. He sued for custody of the kids because I had been evicted from the home we were living in. I understood him taking custody of them, but now I have a great home, I came into some money and found a house in the small town they are living in. I was having problems being able to see them during my allowed visitations because of distance, etc. Well I know live in same little town, actually only a couple of doors down from them. Well, they arent letting the kids come down and see me. They have told the kids that they cant let them come down here because it would make the judge upset that they allowed me to see them when it wasnt my court allowed visitation. If they have custody of the kids, wouldnt it be up to them if they wanted to allow me to see the kids when its not the standard visitation time? Also, I am wanting to know if there is a way of doing mediation right now to put in motion me getting to see them and if we can agree to the custody thing without having to go back before the judge and letting the judge decide. I appreciate any answers I can get. Thank you.

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The parent who currently has visitation with the children has the authority to have them spend time with anyone they want, so long as the situation is safe, and this includes spending time with the opposite parent.
However, I have seen a magistrate get upset with both parties for not "strictly following the parenting plan".
How much visitation do you have? Frequently during the summer the non-custodial parent gets up to 50/50 visitation.