siblings

Good day everyone, it happened to me to have two golden retrievers both are 5 months old, brother (Cheetos) and sister (Tofie).. I had Cheetos first and then just got Tofie yesterday, I know its impossible and unwanted to let siblings mate, and I think I can take care of this point.. My question...

I have a 6 month old golden puppy and now I have the opportunity to adopt his sister, should I? The people who adopted her cannot or do not want to care for her anymore. They don't have time for her so she stays outside most of the day. I feel I should take her. She has not been vaccinated nor...