Explorerhat break out pins

I want to connect three separate sensors via various breakout pins on the explorerhat, and there are only two GND pins available.
As it is only GND can I connect two sensors piggy-back fashion into one GND pin?
If I can make the connection this way I shall make a more permanent plug arrangement, but I don’t want to blow up my Pi.

sure, you can ground many things off a single pin. If you are using the HAT then use the breadboard on top to create a rail or two. Same for VCC.