older siblings in delivery room

I have 13 & almost 11 yr old, & my bfs daughter is 18. The 18 yr old wants to take pics for me- like, not watch watch.. but b in the room. Take pics of when they hand me baby, him cutting cord, etc. Now my 13 yr old is begging to b there too. I told her she would b scarred for life! lol (maybe this would b a good thing? Keep her from having babies? Haha) She doesn't care & wants to see her sister born. 1) is she even old enough for this to b considered? Is there an 18& up rule most hospitals? 2) anyone else had an older child there?