actually could be canon! I mean rosie grows up with John and Sherlock. It would be just natural for her to see them both as her father even if there is no Johnlock at all. That doesn't exclude Parentlock ^-^
I LOVE Mary/Sherlock friendship. While John is the most important, I feel sometimes we overlook how much Sherlock needs Mary too. She supports him, supports John continuing to work with him, and helps so much.