Question

the dispensation dating from
the death of her father on into perpetuity replace perpetuity

Answer 1

It looks like you want to change the wording around “perpetuity” (and note: “into perpetuity” is awkward — the usual phrasing is “in perpetuity”). Here are alternatives and a few rewritten sentence options.

Single-word or short-phrase alternatives
- in perpetuity (preferred legal form)
- forever / forevermore
- for all time
- permanently
- in perpetuum (rare/formal)
- for the indefinite future

Phrases that change the meaning (if you want a limited term)
- until revoked
- for the remainder of her natural life
- for a term of [X] years
- until terminated by mutual agreement

Corrected/rephrased sentence examples
- Formal/legal: “The dispensation, effective from the death of her father on [date], shall continue in perpetuity.”
- Plain: “The dispensation, starting from her father’s death on [date], will continue forever.”
- Limited-term alternative: “The dispensation, effective from the death of her father on [date], shall continue until revoked.”

If you tell me whether you want the meaning to remain indefinite or be limited, and whether you prefer legal or plain wording, I can give a final phrasing.