Ok, if the new parts don't fit then either there is a problem with the parts or you are doing something wrong. Have you compared new parts with old?
Can you explain step by step what you have done so far and where you are getting stuck? I am finding your posts quite hard to follow, and from some of the replies you are getting it seems other people are too. First you talk about discs and pads, then you mention new calipers too? What do you mean "splitting the caliper?"
Does the caliper bracket/pad carrier clear the new disc? If the caliper is actually stuck on the disc as you say in first post then there must be a problem with parts. If it just won't clear the pads then the pistons probably need pushing back further, they should sit flush with the caliper body not stick out at all if they are fully in. Is the piston stuck? Also, are the slides free?
Also, I (or we) have assumed we are talking fronts, but you don't say.
There are loads of knowledgable people on here, give us enough info and we'll try our best to help you sort it.