I've experienced dealing with SDB two ways. In 1994, our bank burned completely to the ground leaving only the vault standing, which besides the currency contained the SDB. Because the entire bank was now in the basement, a ramp was built from the street to the vault. Once that was done, the vault was opened and the nest of boxes were removed and sent to two other branches. Letters were sent out to the customer's explaining what we had done and which location their SDB was at. We asked them to please come and check their boxes content. Customers were very supportive and we only had one complaint. One customer was sure we added something to her SDB! We gave the customers free rent for a year and when the bank was built, the nest were moved back.
In 1998, the decision was made to close a rural branch that had a history of over 100 years and contained SDB. Again a letter was sent out asking customers to come into the branch and remove their contents and close the box. If they decided to open a SDB at another branch, we would give them a free year of rent. The letter gave the customer's six months to take care of this. We had only one hold out that came in shortly before we closed on that very last day.
My experience with both scenarios was this - customer's are great if you keep them well informed and show your appreciation for their patience with us. The free one year box rent helped also.
For when I am weak, then I am strong. 2Cor 12:10