Rights of half siblings

Does anyone know where I can find out about the rights of half siblings?
Two older children of previous relationship have gone to live with their father, going through courts at mo concerning contact etc, he isn't playing ball, contact all over the place if it takes place at all. Their rights and wishes and feelings are all anyone seems to care about. The children from new marriage, well I say new but we've been married over ten years, are not been taken into consideration at all, their wishes and feelings have not been asked and their lives have to work around the other two. I try to get it across that I have to consider them as well and in some ways my loyalty has to lie slightly more in their direction but noone listens. So I have decided I need to find the legal way to push this across.

Whose application is it and for what?

Ex took it to get a residence order, all I want is a contact order.

This is just my layman's view...

Your children are being asked to form bonds with siblings that step in and out of their lives and I quite agree it might be hurtful and disruptive to them. The relationships between the children are significant, important and should be protected. I think your right,a defined contact order might well bring some stability, continuity and be a benefit to all parties.

The first step would be for your ptr to seek a contact order. Your views are entirely understandable and could be used to support such an application but the focus would be on the ex's children's rights (excuse my clumsy grammar) to maintain a relationship with her and of course their wider maternal family.

Maybe I didn't explain properly.

All four children lived with me until recently (there are two from previous relationship and two from current relationship) then two went to live with their other parent, other parent is not allowing contact to proceed as courts dictate despite the exceedingly good contact they had.
The two children at home with me are struggling with the fact they do not see their half siblings after having lived with them for their whole life.
The question is does anyone know the rights of these two children?
The rights of the other two seem to be the only thing anyone else is interested in?
Surely they have some.

When Zonked talks about partner do you mean current or ex?
There is a contact order in place but it is not being adhered to.

So all four children are your children biologically? How old are the 2 with you, what is your contact, and why did residence pass over?

Yes all four are mine, two with me are seven and eight.
The contact order in existence at the moment is every other weekend but ex isn't allowing it to happen. We have seen them about six hours since xmas and not much more than that before xmas.
They started to want to see if the grass was greener over there and I said ok try it for a while.