HCI Acceleration kits are no longer available for purchase (directly from VMware anyway) and while they likely *should* function with addition of new licenses for 2nd socket and additional node(s) (as they are just vSphere + vSAN Standard) unfortunately this would likely qualify as a breach of usage should be you be audited:
"VMware Acceleration Kit (per-CPU) that includes vSphere Standard and vSAN Standard with a ~25%
inherent discount on list price, limited to 3 single CPU nodes per cluster & 1 cluster per authorized
location; includes no upgrades"
Sorry to be the bearer of bad news but do always read the fine print when purchasing licensing (or anything really).