Adding VLAN into Vsphere environment

Hi Omar and Andrew, yes the VLAN and routing were already configured on Core switch. Currently our diagram like this:

ESXi host --------------- vlan 55 -------------- Core switch

As my understanding, you are suggesting us to add 1 more trunk cable like this, am I right?

ESXi host --------------- vlan 55 -------------- Core switch
ESXi host --------------- Trunk (vlan 15,25,35,...)  -------------- Core switch

In case I change the settings lile Omar's advise, is it right?
ESXi host --------------- Trunk (vlan 15,25,35,55,...) -------------- Core switch

If we add a port group of VLAN 15 and connection is remain in VLAN55, is it ok with the VM in VLAN55? If we configure the interface (on Switch side) from access mode vlan 55 to Trunk mode, does it affect the VMs? Do we need to change anything in ESXi host?

Make sure ALL vLANs are consistent on the trunk port and connected to two vmnics in host!

These vmnics are connected and active active to vSwitch

Then create your VM portgroups with correct tag and label

Then assign that vm portgroups to VMs via network interface per VM

And with ALL network changes it can affect VMs in production if not done correctly!

If unsure stop and complete changes outside service hours!