Welcome to PetTalk. Glad you found Marley before she got hurt by a car. I wonder if she had climbed into the underside of the car from another location, and ended up at Kroger's parking lot? That happened with one of my feral born kitties Amy. The darlings had ripped open the screen a few years ago, and a couple got outside. I knew Amy was out (she'd done it before) but I couldn't find her. I had to head out and pick a cat up that was slated for euthanasia and stopped at WalMart first. I came out to hear a cat crying and sure enough it was Amy who had rode under the car for several miles. I managed to get her safely into the car and was so shaken by that incident! I think it's a good idea to get Marley to the vet to rule out FeLV etc. before exposing your other kitty to her.