The most common recommendation and standard industry practice is to transplant palms during warmer times of the year -- preferably in late spring
or early summer -- because a long growing
season is available for the regeneration of the root system.
Having said that, I've just noticed that your from Calgary, so I assume you won't have your palm outside year 'round? lol
Re: cutting vs. pulling apart of your parlour palm, carefully pulling them apart is best: plant
maturity tends to influence the functionality of the root initiation zone
in younger palms, and therefore impacts their ability to regenerate roots after transplanting -- with cutting, it is much more difficult for the plant
to sprout new roots.
Hope that helps,