Since you know kind of where they are, including the ones that are peeking out, it's OK to get to them now. Just be careful digging as you now have not only the bulbs to be careful about, but also any growth that is still underground that can't be seen.

After doing that, I would mulch the area. That will hide the digging and also make the new owner think he got some nice mulched area also. You can leave him some surprises, though...maybe some inexpensive seeds of some annual or perennial plant to make up for taking the lilies.

To me, it's always fun to see what plants come up at a new house. Who knows, we might see your new owner coming here to help identify some plants.

I have transplanted many lily around this time of year, most of the time turned out well. some hints i'd recommend are to make sure you dig wider and deeper than you expect. my asiatic's are prolific so whenever they had to be moved, it was easy to leave some behind for the new owners.

i also love finding out what plants are at a new place. i've found a lot of treasures