Great question! Sorry for the delay in answering. I haven't been back on the board for a bit.

In the past, we have allowed and encouraged copying the student books within the family unit. We wanted to do everything possible to help families use DITHR.

However, in the last year we have been finally changing our copyright policy on the Student Books with each new reprinting (after over a decade of allowing them to photocopied for family use).
It is not without thought that we are changing our policy, however we continue to run into really blatant misuse of the policy. We hear from people fairly regularly who have purchased an entirely photocopied Student Book of ours (on a used board or ebay), and then call or email us wanting us to supply pages missing from their copy.

We have had people copy the Student Books in co-op settings for entire classes without permission. We've had people in the checkout line at convention tell their friend not to buy the Student Book because they will just copy their Student Book and give it to them instead. At used Book Sales at the conventions we attend, someone usually points out to us that they bought the Student Books for DITHR in a binder at the used book sale, all copied for them, so they only need to purchase the Teacher's Guide. So, at this point in time, we have been removing the permission to copy for family use from the copyright so that the copyright is more in alignment with what other companies do for workbooks such as ours.
You are so gracious to ask, and we have learned the hard way that it is wise to limit the copyright.

We pray you will enjoy your time spent with DITHR as much as we have.
Blessings,
Carrie