Since there is no option to merge table cells in Google docs, creating a new table inside a cell could be a possible work around for this.
When I insert a table inside a table cell, blank lines are inserted before and after the table. How can I remove these blank lines? or create a layout similar to the one shown in the picture below (without the extra lines in first column)
I have tried playing around with cell padding and minimum row height in table properties but found no solution.
As far as I know it's not possible to remove the line before and after the nested table. The good "news" are that now is possible to merge cells.
References
Add and edit tables - Docs editors Help
Merge cells and wrap text - Docs editors Help
How does merging help?
To create complex table structures, starting from the most nested cells you will need and merge cells to achieve the larger cells.
Example:
+--+--+--+--+--+
| | | | | |
+--+--+--+--+--+
| | | | | |
+--+--+--+--+--+
| | | | | |
+--+--+--+--+--+
| | | | | |
+--+--+--+--+--+
+--------------+
| |
+--+-----+-----+
| | | |
+--+-----+ +
| | |
+-----+--+--+--+
| | | |
+-----+--------+
