Simplify inserting rows into a table.

1) It you want to easily insert row in existing "triplet of rows" select middle row of the triplet, insert 1 row and then
-- copy/paste special values only from 2 bottom into 2nd and 3rd
-- select 4th row (now duplicate with 3rd) and Delete (contents) - all line types and merging is retained, and you have emtry row 4 for writing additional info.

2) If you want to add a new "triplet", select 3 rows staring from the row where it shall start. Then right-click on rows numbers and from pop-up Insert. Finally copy empty triplet at bottom of your sheet into 3 newly inserted lines - it will retain formatting (merging, borders etc.).

Glad to hear that, and thanks for marking thread Solved, and for reputation point