Doc2015,
One combined B4 is enough per family. NOT separately. However, consider the following
I had one "Good Accompanying" form and I used more than one form for 'Good to Follow' as they would come from different locations; different time frames, also on two separate names (both adult parents) as I was sure one would be in the country to receive the items.
Also do not hesitate to include any and sundry in the list. You need not bring them eventually but it helps to list them as they can be brought duty free for as long as they are recorded in B4/B4A forms. Furnitures; Permitted Vehicles; sports equipment; Jewelry; etc. Hope it helps you plan.