Interesting! I had no idea about any of that; I simply planted my Liberty and started harvesting. And even though it’s now a frankentree, for quite a while the only pollinizing partners it had were whatever the bees and wind happened to find and bring. There’s a lot of conflicting information on the different websites I looked at. I think you’re going to have to get the answer from growers.
I’m not clear on why you want an apple or crab with similar resistance. Is it because you hope to cross with the Liberty or are you considering making a different choice?
If you want to grow a Lib but are concerned about getting adequate pollination you might consider grafting two or three suitable varieties on the tree. I was surprised to see the suggestions for adequate pollinizers on the Orange Pippin catalog:
But frankly, I don’t think you have to be too concerned, if my experience with my one tree is any indicator.