Is there a way to auto close a CTA when you are using unique identifiers in the CTA?

currently we create CTAs under the same reason code by using the "unique identifier" checkbox. Is there a way to auto close these CTAs when the case closes? I tried the auto close but because of the unique identifier it just finds any old CTA that is with that reason code and closes it. I need a way to sync up the two items somehow. We are thinking about using SF workflow rules to accomplish this but before I jump down that rabbit hole wanted to see if anyone had done this differently. 
We use date fields. So if we know a specific CTA is going to close in a certain time, we make sure that the rule only applies to that certain time. The other option is to create a new object with the unique identifier and make sure that object is in the criteria or filters of your rule.
Good idea but will not work for us unfortunately. That would be a lot of different objects 🙂. We have CTAs that use the unique identifier checkbox for the reason and name for instance: "Warning Service Request 459821 (this is the unique identifier) has been open too long". We never know how long that Service request or incident or work order will be open so dates will not work either. Thanks for the idea though love it!
Andrew, I am kicking this into an idea so product has visibility into this. I tried to create a rule to close them, but couldn't get it to work properly.