Tag merging feature is in our to-do list. 

I had a different question, I'm happy to repeat "How can two (misspelled) topics be joined?".

If renaming a topic is not the way (for some tech reasons I don't care about) then how can we solve the use case outlined above? 

And if there is no solution, please say so and take this as a feature request. We have some 400 topics - which can probably be merged to less than 100. And I'm sure other WP-Forums have the same problem. Your's for instance with 831 Topics - not useful at all for a reader...

Thanks much!

There cannot be 2 tags with the same name, you have to edit the topic and change the tag name to the needed.

I'll try to make myself more clear with some screenshots:

Here are the two topics:

 Then we try to rename the misspelled topic:

Instead of a dialog "This topic already exists. Do you want to join the topics?", we get an error:

So again: How can we join the topics?

I don't understand what you mean, saying how can we join topics.

About the parental controls and parental control part, you need to edit the topic and rewrite the topic title as you need.

Now we would like to join misspelled topics. Just renaming the misspelled topic (using the Topic Manager Add-on) does not work unfortunately. No error is show, and topic name is not changed if an existing topic is used.

So the core question is: How can we join topics?

Thanks.