We would need 2 enhancements for the nat44_add_del_lb_static_mapping API:

• local_num needs to be more than uint8 - the current type limits NAT LB rules to max 256 backends
• we would need a way to add/remove backends (locals) without the need to delete & recreate whole static mapping (e.g. in case of 3 locals existing, and the need of addition of 1 more, we do not want to touch the traffic for the existing 3)