yeap very trival todo, you use the bonded-interface name in your vlan-subintf
i.e here' s one of my 620 connected to a Nexus
config system interface
edit " bond0"
set vdom " root"
set type aggregate
set member " port1" " port2"
set alias " bonded to nexus 7K "
set algorithm L3
next
end
edit " vlan-DC01-SW1"
set vdom " root"
set ip 172.16.199.11 255.255.255.0
set interface " bond0"
set vlanid 178
next
edit " vlan-DC01-SW21"
set vdom " root"
set ip 10.11.0.11 255.255.255.0
set interface " bond0"
set vlanid 888
next
edit " vlan-DC01-SW31"
set vdom " root"
set ip 172.16.88.11 255.255.255.0
set interface " bond0"
set vlanid 23
next
end
Just adjust the switch and FGT for the load-balance algorithm to achieve your desired balance.