I don't know if I think the extra barks as payment would work but I could see it work with the exact amount of barks needed to put her in heat, just like using a lion scrote. I do have some questions of functionality though, if you dont mind! :D
1) What if there happens a RO between sending the request and the owner accepting it, you know I send it when she has 14 cooldown days left but the owner accepts when there's only 13 days left? How would that work with getting the bark(s) that aren't going to be used for the heat, due to the breeding cooldown naturally lowering with RO, back? Would it automatically return to your inventory upon the lioness owner's RO or would only the barks necessary for putting her in heat be used when accepting and then the unused bark(s) would be send back upon succesful breeding?
2) How would one go about securing that the person providing the barks is also the one to receive the heat? Let's say I send a request with barks but the lioness doesn't become pregnant on the first try and then the owner cancels the request but now the lioness is in heat with my barks but I'm unable to breed her. (That would obviously be against the site rules but that's never stopped anyone before). Would the lioness have to be either goddess fertility or have a black stallion/angelic blessing equipped to ensure that the one providing the barks also is the one to receive the heat or would the barks only go into effect when the owner clicks "Accept" and then if it's unsuccessful cancel the effect, a bit like with a scrote that only go into effect upon a successful reverse breeding?
I don't know if 2) makes sense but what I'm thinking is it goes directly from 14 days of cooldown to pregnant and the barks has then been used. Usually though, you can't accept the request if she isn't in heat, so that would require some rewriting of the code used in accepting heat requests but I don't know if it would require a lot of work or if it's just something minor that would have to be changed nor do I have any idea how that would work with already existing mechanisms.

Anyways 100% support, it would be nice and much easier, and hopefully wouldn't rely as much on trust as it does now. I'm also sorry for any grammar mistakes, English isn't my first language, so let me know if I need to rephrase anything or explain something differently! And sorry for the long questions

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I'm thinking that barks would only be taken after successful breeding and yes it would be returned if it rolled over
Something like rollover update:"one bark has been returned to inventory due to sooner heat" or something like that
I'm unsure of how difficult it would be to code such things unfortunately

No worries I am happy to have the questions

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