How to have hidden rows that can be made avail by drop down menu.

Supposing I have the stats of a game piece in a row and I wish for my game piece to have the option of being mounted, such as cavalry. The mount needs to have his own stats as well but I don't want to have the column stats always displayed. I envision that his rider, say in column number 4 of the sheet1 (attachment provided) has a cell (BQ) that will check if there is a mount. If it is left blank then no mount is required and thus the column below remains hidden. If the mount cell has a check mark then a column below number 4 opens which will provide cells to be used to display the mount stats.

Is something like this possible?