If you dug them up with plenty of soil left around their roots and replanted them in a nursery bed which is, perhaps, more gritty than your regular garden, gets plenty of sun over the cooler months, and shelter from the summer scorchers, and leave them to grow on.

Depending on where you are you might also need to protect them from munching creatures and frost heave. In Nature there are usually plenty of seedlings to cope with the natural thinning process but you've only got three.

You probably also need to mix in some soil/duff from the area where the parents were growing because many pine trees need to work with their own brand of soil fungi to grow well. You could also mulch with old needles or bark chippings but not too close to the stem.

If tall and stately is the result you want them you need to plant them quite closely in three to five years time, when they've developed a good root system. Many pines, when planted with a lot of room to spread, do just that.

In the year before you lift them you will probably need to undercut the roots so they can first grow new feeder roots and so you can lift them later with least stress to the trees. Check with your local forestry people about the optimum planting time/s for the species you're growing.

Unclear if you want them to grow where they presently are.
If so, you could do nothing, and later choose the strongest of the three to grow in that site since they are quite close together, no?
Or you could dig them up now. It is not difficult and is usually successful.
Or you could leave 2 and dig up one, or leave 1 and dig up 2.
Over the last 5 years I have dug up lots of pine & conifer seedlings....really, it is a piece of cake, easy. It does take some years for them to attain size however.