You do not want to place two Advance Termite Bait Stations next to each other, if you have activity. The label does not permit this, and also you could possibly disturb the colonies entry trails into the other station by digging into the ground. Termidor SC is the only liquid that you would want to use near a termite bait station, but you can only place Termidor SC next to the foundation of the structure.
Advance Termite Bait Stations should be placed 2-4 feet away from the foundation. They should be spaced 10-15 feet away from each other.
We would not recommend using the termite bait stations due to the fact that you have a crawlspace and are on piers. To make sure you prevent termites you want to use a liquid Termiticide like Termidor. Please review our article Barrier and Soil Treatment.
Foundational walls and piers can be treated with a termiticide (Termidor SC) at the soil level: