Landlord revoked HSPTA new legal rent by forging leases

Tenant on SCRIE 7 years, elderly, 25 years in same apartment. New landlord bought building, warehousing l, then speedily deregulating, Elderly complained to HCR with RA89 and RA 90. The owner forged lease by whiteout after elderly signed and then revoked new LRR a which is in bills 2019-2021, in rent history. Owner never registered at SCRIE, adding various illegal SCRIE and billing for 2 years 25% above allowed. Now elderly requested: to void forged lease, to issue renewal with same $ that in weekly SCRIE reports, in rent history ( which owner changed 3 times and last one is correct, but bills are not correct). In order to prove his fraud Owner created second lease dated later than first lease and it was sent to HCR during active processing case but never sent to elderly tenant. He now threatened if elderly not signing improper lease with revoked HSTPA LRR, he will reject renewals and will holdover and evict. He is tampering mail if tenant, not letting HCR mail to be delivered. Advise?