neeed some help on PR applicatin

My friend bought his family under dependent visa september 2008. he is a British citizen. they got the visa on july but came here on september. now they are competing their 2years stay in this country on september since their arrival. but their visa expires on july. he wanted to apply for PR for them. ( i suppose he can apply PR for them after 2 years stay in here).
now problem is, his 2 daughtrs are over 18. youngest one is under 18. now what he has to do? for the over 18 chilren to apply to renew the dependent visa and re-apply for PR after september? will their age affect any of this processs? or can ask for PR on july?
i guess the under 18 girl and his wife can apply for PR on july? is it correct?

please help.
Thanks in advance

See also Applying to settle here if you delayed your entry to the UK. i.e. Apply by post before visas' expiry.

How to apply for settlement in the UK > Form SET(M):

Can I include my dependants in my application?

You can use one form for a joint application by you and any children aged under 18, if they are applying as your dependants. Children over 18 must apply separately, using application form SET(F).

Don't forget to enclose a covering letter linking the elder child's application with your wife's.

KOL required for adult settlement applications.