Hi,
Before making any changes to the suspension check that the seat is actually a low one, because if it isn't a low seat will do the job fine. Is there anyone near where you live with an F650 so you can swop seats?
I'm 5'3" and the low seat suits me fine.
I can highly recommend FTR Suspension in Bury St Edmunds, give then a call they may be able to give you some advice or give a decent quote or doing the work. They do all the work for the local BMW dealer so they are clued up on BM's. Both my husband and I had progressive rate springs fitted by them, really helpful and friendly
http://www.ftrsuspension.co.uk/home.htm
I also have Wunderlich adjustable clutch and brake levers which come in close enough so I can reach them easy with my little hands, just something else that may make the bike a little more easier for her.