Cats and dogs and other mammals that have more than one offspring at a time can have a different sire for each offspring. (Technical term: superfecundation.) That still doesn't affect the NEXT litter. It is simply biologically impossible. I don't have to be "an expert on cats"... I have a fairly solid understanding of biology and genetics. The "bloodlines change" is, simply, impossible. Whatever old wives tales people might believe, it is, in fact, not biologically possible.
This forum or any forum, anyone with a basic biology and genetics understanding will tell you the same thing if you post that.
You aren't the only person who has wondered/thought the same thing. So... here is a professional answering it, with also an explanation.
What about future litters? There is never any lasting affect from the genetic input from a previous father. So you can breed her to any male you want after this. <<
https://www.drjeffnichol.com/different-fathers-for-the-same-litter/