Hey @tony-duke,
as mentioned by @syedumair, this is not possible to implement in steeditor due to limitations in Steem. Steem allows beneficiaries to be set only once and only as long as there are no votes or comments on a post. You can't edit beneficiaries once they are set. Additionally, you can only have up to 8.

However, are you aware of @steem-bounty? This allows authors to set a STEEM or SBD bounty for comments on their posts. I think it follows the same goal as your suggestion. Check their FAQ for more details on this!