Seating Arrangements??????

I am looking for some advice on the seating arrangement for my wedding. My fiance`s parents are divorced and do not get along well (really the stepmother and mother). We are looking for a good way to seperate the two sides of the grooms family as to prevent any unnecessary tension or problems. Thus, we do not want to have a Bride`s side and a Groom`s side because we don`t want to mix the Groom`s mothers family with the Groom`s fathers family. We are having an outdoors wedding in a garden area. My only idea is to have 2 isles and seat the my family in the middle and the Groom`s mothers family and the Groom`s fathers familiy on each side. The only problem with this is that then there will be 2 isles rather than one and more people will be seated in the middle section than on the sides (since we would be splitting his family in half). Does anyone else have any suggestions???? Thanks!