Office 365 - merge cells

You cannot merge cells in a structured table.

Merging cells is almost always a bad practice anyway. I would design a solution that does not require merged cells.

Edit: You can use Center Across Selection (horizontally) in a table, which can give the appearance of merged cells without actually merging them.

As Jeff has implied, merging cells is NEVER a good idea. Don't do it - you don't need it.

Ok, but the users of this excel files don't want to have duplicates in the table, they need a function that merges them somehow.

The users need to be told that aesthetics are not important.

What you want is going to get in the way of what you were asking for yesterday - inserting rows.

Your job is to convince your users that looking pretty is irrelevant - the data table needs to be FUNCTIONAL, not pretty.

Tell them that they can't have merged cells. End of. They might want them, but they don't need them. You will save yourself a lot of hassle by doing so.

Maybe with some conditional formatting we can 'cheat' a bit like below:
Capture.JPG
Please check attached file.

p.s. <LANG=PL ON>pozdrowienia dla Moniki :-) </LANG=PL OFF>