Wow, it's a little hard to tell who's who in the pictures of Sirabe and Ki playing together! They sure look like they're related- It would be really cool if your parents would let you keep her (provided she has no where else to go) -- she & Ki are way too cute together!
Good luck with her. Maybe someone not in the family let her out - that's what happened when my Star went out for a walk in the neighborhood. Stupid roofing guy let her out . At least she's safe with you at the Muttlies doggie spa! - swimming, rubs, soft bed, fabulous food...