Old
A single service site may host one or multiple service contact instances.
New1
A single service site may host one or multiple service instances, and one or multiple related service contact instances.
Or New2
A single service site may host one service instance for a given service, and in this case one associated service contact instance; meanwhile, a single service site may host multiple service instances for a given service, and in this case one or multiple associated service contact instances.
Reason of suggestion:
It is a little hard for a new reader of the draft to understand the relationship among a service site, service instances, and the service contact instance.
IMHO, more explanation should be added here or someplace else.
In the introduction,the 4th paragraph,
Old A single service site may host one or multiple service contact instances. New1 A single service site may host one or multiple service instances, and one or multiple related service contact instances. Or New2 A single service site may host one service instance for a given service, and in this case one associated service contact instance; meanwhile, a single service site may host multiple service instances for a given service, and in this case one or multiple associated service contact instances.
Reason of suggestion: It is a little hard for a new reader of the draft to understand the relationship among a service site, service instances, and the service contact instance. IMHO, more explanation should be added here or someplace else.