I've had a text from my daughter's friend's mum asking for her to go to their house for a play-date. Trouble is, my daughter (11) says that this friend has access to unsuitable internet stuff on the tablet and computer in her bedroom. (We don't allow our daughter to use a computer or tablet without supervision.). This mum has also shown her daughter (also 11) sex-education videos and also shown her how to use condoms. I do not know this mum well - only small-talk at the school gates occasionally. We haven't wanted to really encourage this friendship as this friend blows hot and cold with my daughter and also because my daughter gets worried about the things this girl says - that an 11 year old shouldn't really know.... but my daughter really likes her and wants to go on the play-date. We are not keen at all, but if I say we are busy this week, she is just going to ask for next week, etc. What should I do?