When you create a LAG (let's say master = 1:4 and group = 1:4, 2:4) the master port represents the group for switch vlan configuration.
That means the switch will consider this LAG as port "1:4g" where "g" means Load Sharing port.
Based on that, when you do "configure vlan add ports 1:4 tagged", all the LAG will be applied/configured to that vlan.
When you do a "show vlan " you will see the following (based on above description):
Tag: 1:4g
If the master port goes down, traffic will be shared to the remaining ports.