Hi Jingshine, You can. You need to fulfill the requirements by law that any Mexican citizen needs to fulfill in order to be able to adopt a child. It's a complicated process, and working with a lawyer is strongly recommended.
kimanjome To answer your question, you don't. You don't pay any of the days they missed work. Regarding the IMSS, I would advise you to become their employer, this is mainly to avoid any issues with IMSS. Don't worry about feeling like you're running a business out of your home, it won't be the case; but it is strongly recommended to have a special contract signed with them.