George Lewis here, I am the president of the Catoctin Aqueduct Restoration Fund, Inc. – many thanks for your interest in the Catoctin Aqueduct.
The norm is one adoption certificate per adoption; however, we could stretch this a bit.
Suggest you get back to me with the number of certificates you have in mind and the type (and adoption fee donation) of stone you have in mind; keeping in mind that the objective of the Adopt a Stone project is to raise funds to restore the Most Beautiful Aqueduct on the Line, and that each certificate costs $4 to print and $1 to mail.