How to properly merge two tables in MS Word
Quite often you’ll find that you have two tables in a Word document and you want to join the two together to make just one table. The solution is simple but way from obvious.
To do this, first select over all the cells in one of the two tables. If the table is underneath the one you want to join it up to, then press Alt + Shift + ↑ to move the table up the document so that it joins the bottom of the table before it. Keep pressing the key until the top row that you have selected joins the bottom border of the one above.
If you have selected the topmost table, then press Alt + Shift + ↓ until the top table locks onto the table below.
You can also drag one table up or down until it joins but this method is very slick. It also works on a single row so you can take one row from one table and move only it to join up with another table or to become a table all of its own. Experiment with this key combination – I’m sure you will love it.
Once you’ve done this, the tables will be joined to make one single table. If desired, you can then adjust the positioning of the columns so that the columns match between the two tables – this isn’t required but you may want to do it if the columns are supposed to be the same throughout.
From allexperts.com:
There are a few things you can check on:
Make sure that the second table doesn't have any rows marked as heading rows.
Make sure that neither table is wrapped (wrapping should be set to None on the Table tab of Table Properties).
Make sure that neither table (even if they appear identical) is nested in one large cell of a containing table (this sometimes happens with material pasted from the Web).
That said, I can tell you that I once had two tables--which I had created myself, so I know there was nothing unusual about them--that just refused to merge, for no apparent reason. It's possible that the table structures were somehow damaged, and if I'd been doing this in Word 2003, perhaps using Open and Repair would have fixed the problem. As it was, it wasn't vital that the tables be actually part of the same table, so I shrugged and moved on.
If you encounter such a situation, you have really only two recourses (if Open and Repair doesn't help):
Add rows to the first table and copy/paste the content of the second table into them.
Convert both tables to text, then convert all the text back to a single table.
Sorry I can't be more definitive, but this is a mystery to me, too!
Suzanne S. Barnhill
Microsoft MVP (Word) 1998-2006
Similar situation I had was resolved by adding a blank row to the bottom of the upper table and a blank row to top of the lower table. Neither of these two new rows should have columns and both tables should be the identical width. Then, by removing any returns (blank lines) between the two tables, they should automatically join. Afterward, you can remove any unwanted rows.