Can you set an indexer as a "backup"?

I got access to another indexer and I thought I'd set it up in case it's able to grab things that my main one can't. However, as I'm just using the free plan for now, I keep getting errors about API limits for that indexer. Is there an easy way to set the new one as a "backup" and only use it for missing things that the main one can't find?

I thought about something with tags, but that seems like a lot of manual work? Thought I would ask if anyone has a better solution I hadn't thought/heard of?