@MJ You will have to modify claims rules so that they know specific VDI host needs to go to specific tenant, which issuerID claim to issue.
http://VALIDATEDDOMAIN/adfs/services/trust/ needs to be one of issuerIDs on one of federated domains in a target tenant. So there will need to be more conditions in that issuance urls and just filtering on SID of domain computers group is not enough.
You can duplicate the rule so that it look like this
c1:[Type == "http://schemas.microsoft.com/ws/2008/06/identity/claims/groupsid";, Value =~ "-515$", Issuer =~ "^(AD AUTHORITY|SELF AUTHORITY|LOCAL AUTHORITY)$"] && c2:[identify OU for target tenant]
=> issue(Type = "http://schemas.microsoft.com/ws/2008/06/identity/claims/issuerid";, Value = "http://hardcodedtargetdomainname/adfs/services/trust/");"
You will need to have it however many times you have target tenants.
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