Can legal heir of deceased person execute retirement deed

Two partners were running the partnership firm. Out  of which one expired. After death, the partnership firm will automatically dissolve and become propietorsip of the remaining partner. Now the remaining partner, legal heir of deceased partner and the new partner want to execute a admission-cum-retirement deed in which the deceased partner will retire on his death and new partner will join. The legal heir will sign on behalf of deceased partner. Is it lawful ?