I found the link below, I hope it helps.

In PA they are endangered. They are so dependent of special factors its difficult to transplant them. They are so rare here, Ive only seen one in my lifetime. Perhaps you could call an eviromental agency in your area for advice.

Here is a link that might be useful: lady slipper discussion

"Can we transplant them to somewhere else on the property?"

Yes

"Will they survive the transplant?"

If you are careful w/ digging and site selection, if they are currently healthy/robust they should survive nicely.

"I remember hearing that it is illegal to dig them up but if it is on your own property is it still illegal?"

No, it is not illegal to move them on your own property. There is a lot of misinformation about this.... which is good in some regards.

"what is the best way to transplant them?"

Mark them now. Find a suitable site w/ soil/light conditions similar to where they are currently growing. They generally like airy, moisture retentive but freely draining soil that never gets too hot or dries out completely for too long. Addition of sand or perlite sometimes helps create freely draining soil. A very light mulch can sometimes help keep soil cool and moist. Dappled sun or sun during cooler parts of the day (early morning/late afternoon) is best. Transplant them when they are dormant in cool early spring or fall. When digging try to get all the lateral roots without severing them or distubing them too much. Roots can spread a foot or more in all directions in the top inch or two of soil. Plant at a similar depth to how you found them with roots spread laterally and root tips pointing slightly down.

Lab propagated plants are increasingly available for purchase. If responsible growers are supported hopefully some of the pressure on wild populations will be reduced. Rescue is a good thing. These plants should never be taken from the wild just for cultivation.

Good luck!