Margot, the solution is just to let the atmosphere bring the moisture back. With 6-8 weeks at about 100 degrees F. and no outside air, it really was dry, probably well under 6% EMC. Normal inside heated EMC is about 6% and summer EMC's seem to run 12-14% here in southeast Michigan. I would be a little concerned about pushing moisture restoration too much. It will come back on it's own with outside air, showers and dishwashing in the house and similar activities. You do need to get the moisture back to even through the wood and that just takes time. I would guess that 4-6 weeks exposure to "outside" air and there isn't much that you can do to help that would not have the potential for future problems. Excess humidity, over 20%, is an invitation to mold and mildew.
One thing that I might suggest is checking the actual EMC readings. Perhaps you can borrow a meter or ask someone that has one to check it for you. If you have a saw mill in the area, that would be a place to start--and meet the neighbors.