Pill bugs, sow bugs, cousins and land dwelling cousins of lobsters are part of Ma Natures recycling machine and live primarily on decaying vegetative waste. What are these wee buggers doing that requires someone "to get rid of them" in any way? These guys are seldom the real reason for living plant loss, but they get blamed for that becasue they are there cleaning up when people see the damage and the real culprits get away with it.

Brian, tell your sister to incorporate horticultural grade diatomaceous earth in the mulch, soil in the plant beds or containers. She might want to make sure that the area isn't getting overwatered, as well.

She can find the DE in garden centers or the garden department of most home improvement centers.

A population reduction IS necessary when there is a severe infestation. I don't know why everyone argues this matter.

If you have NOT had an infestation problem where pill bugs are problematic, this is not an indicator that others should not do something to rid themselves of pill bugs.

Here is a link that might be useful: Discussion on diminishing sow bug population.

Many people seem to have a lack of knowledge of the role the Pill Bugs, Sow Bugs, Wood Lice, etc. have in nature and so they ascribe the wrong interpretation to what they are and the role they play in nature. These wee critters need a cool, moist environment to live and reproduce in and if you provide that you will have an abundance of them, along with other critters that prefer that same environment that most likely caused the problem you are blaming the Pill Bugs for.
I also understand there are those that no matter how many entomologists I use as a source there are those that would rather believe myth and folklore, but I offer the link below for those that would like to educate themselves.

Here is a link that might be useful: About Pill Bugs