cluster with 3 appliances

This is certainly possible, to do this you will use device and traffic groups. Device Groups to define the cluster members, and traffic groups that define the services that are active on which cluster member.

Active-active config https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip-device-service-clustering-admin-11-5-0/3.html

Device Groups https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip-device-service-clustering-admin-11-5-0/6.html

Traffic Groups https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/tmos-redundant-systems-config-11-2-0/6.html