Merging rec'd emails

Somehow I have emails from one email address which has two different descriptions (unsure if that is the right term?)
So as an example.
Fred @ Fred Does it All
Fred @ Fred Does-it-all. The proper email address’s are identical.

How can I merge them under just one ‘description’ ?

I would suggest more clarification.

It looks like it is the ‘name’ part that is different for one email address. It only exists in my contacts in one of the versions.
The headers of two emails from the same email address could look like this.
“Fred @ Fred Does it All”
“Fred @ Fred Does-it-All”
The difference are the dashes.
I want them grouped together but the section in quotes keeps them separate.

Did anyone answer this question?

Grouping messages into a conversation is not possible manually. Or it is possible, but it involves exporting the messages, editing the header, and importing the message again. I think for the average user or for regular use, that is not practical.

But for your scenario Rob, why don’t you just cerate a separate folder for each wedding party? Then drag any message for that group into that folder.