yes!! lol I was reading the 3 mice a wk saying ouch lol!!
It is much much more healthier for your boa to move up a size rather then feed more then one prey item! If you feel your boa in size due to refusing meals go from every 7 days to every 6..still this would be much healthier then more than 1 prey item.
think about how much more your feeding your boa weight wise by feeding him 3 prey then maybe 1 size bigger prey. its a big difference, can cause your snake to grow too fast or a even stress and have a regurge.
and rats are soo much better for your snake then mice, rats have higher bone density and there for have more protein in them so if your boa is feeding on mice move to rat pups or weaned
good luck!!!