Couch surfing with a toddler?

my family and i have a scheduling conflict. I have a job interview and so does my mom who was supposed to watch my son. Her interview is in another town and i can't really reschedule. My mom and sister and going through the couch surfing network and said they can take my son along. I have tried to express how uncomfortable i am. My sister has joint custody of my 21 month old and she is able to take him when she wants. She is saying she wants to. What is your take?