Depends on what the difference in value is Ivo.
Also if earless he only sells for little money then why bother separating. Unless the bit he earns you pays towards reducing the cost of the dog.
If you love the dog, and have the money, then why not experiment with the cat. Get the resin repair done, see if you love him more once you have an invisible (but reversible) repair done and they sit as a pair. If not, sell him and hope to make back what you paid for him plus the cost of the repair. If you don't make it all back then yes it makes your sole remaining dog more expensive but you might have learnt from the experiment of the resin repair.
I am hopefully having a repair done on a beautiful piece of glass. But it's worth it because the actual piece wasn't inordinately expensive and even with the repair on top it would hopefully pay for itself IF I ever sold it, but in my heart I know I'm never going to sell it. So it's worth it to me. I've not considered a repair on any other item unless it was one I knew I would want to keep - I don't have the funds to experiment
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