i see your image now
the SMLT and LACP links must terminate on the same vIST cluster. So in your example you can't have switch stacks going to a vIST cluster spanned across two DC's and then support MLAG to the servers in the same DC.
in your example core A1 and B1 must be in the vist peers for each other. But that would break your LAGs to your servers.
the only way you could do this is research what kind of NIC teaming your servers support. Some servers like ESXi and Microsoft have an L2 teaming feature that doesn't require a LACP LAG on the switch side. you only need to configure access or tagged ports.
