Serving papers to multiple previous tenants in multiple addresses

Old tenants (5 on lease) owe 7 months back rent, currently moved out and I plan on suing them now for back rent + damages. Although 5 were on lease, one of tenants ex-wife lived there as well. The forwarding address of the old address is on Judith street, where the ex-wife lives. 3 previous tenants live & own in 2 different homes who we will go after. When I file the small claims, do I have to serve in all 3 locations? Or can I serve and subserve everyone to the forwarding address? Also, should I be using a processing service or can I have the courts mail out a certified letter to the locations?