Need help pricing for 60th anniversary photo

[bellacat]

I just got an email from a referral for a 60th anniversary photo. This family found out about me from another photographer who gave me the referral since she is already booked that day for a wedding. Yay for me but i haven't had a session this large so I am not sure what to charge. I don't want to charge too much but then again I don't want to not charge enough.

Its a family with 4 children and their families. They want a large family photo and the individual shots with each child with their children. I normally charge a session fee of $100 per family up to 4 people and $25 for each additional.

I really could use your expert advice.