Of course. We understand that photo collections are very unique and personal things. Sometimes photo collections being sent to us are gathered from different members of the family, different peoples' houses, or are simply from different eras and are not stored in one tidy collection.
Anything that arrives to us in an obvious batch, or ordered in a particular way, will be kept in that order and in that batch. The digital copies you receive will be decipherable based on how the originals were packed, and the physical copies will be returned in the same order. Some people keep things together using elastic bands, or place batches of photos in envelopes. In fact, if you do use envelopes and write on the front of the envelopes, we can scan the envelope too, so that becomes the first scan of that batch.