Unfortunately, my crystal ball appears to be cracked and my psychic skills are sub-par today. As a result, I'm unable to divine the version of RoboHelp you may be using.
In later versions of RoboHelp, you have the capability of selecting across a block of text, right-clicking and choosing to Add to > Snippets.
Kind of curious about why the need for as many as you think you may be needing though.
Also, if your goal is to have a snippet be a row of a table, I'm not sure that you will be able to realize that goal. I note that when I have a table and select the row, the context menu DOES present the Add to bit, but Snippets is disabled (or greyed out as so many like to refer to it). So even if you were able to get a table row added as a Snippet, it likely wouldn't work well to seamlessly insert into an existing table or even append onto an existing table.
I found the same as Rick but wondered if you could create the snippet and then add the table directly into the snippet, maybe at HTML level. However, like Rick, I think it might not insert neatly into another table. A bit of trial and error in a dummy project maybe?
See www.grainge.org for RoboHelp and Authoring information
Yeah, I just tested this in a dummy topic. I had inserted a table consisting of two rows by two columns.
Then I added some text to each column of one row.
I then selected the row and changed to HTML view. Copied only the TR down to the /TR tags.
Added that to a snippet. I had to simply switch to HTML view in order to add it.
Upon adding the snippet to the existing table, it wasn't quite what I'd hoped.