The re-grant in the form of four leases should be ok: see SDLTM11070. I don’t think that the fact that the original lease was assigned makes any difference as it is the identity of the parties at the time of surrender and regrant which counts. Additionally although one of the new leases will be charged upon the release of the charge on the surrendered lease, I doubt that this can be treated as chargeable consideration under para 8 Sch 4 assuming that the tenants are just transferring the same debt to one of the new leases.