The opponents open 2D multi, we must make a double that shows 12-14 points and balanced (with a 5 card major just keep it simple and bid the major rather than double), don't worry about your shape, you don't need both majors to double a multi. Do NOT pass with an opening hand or else it will lead to uncomfortable auctions and bad results.
The most important signals
Try not to double with a 5 card major
Bid as high as possible!
Defending against a multi 2D
Always transfer with a 5 card major.