Hi
I wasn't suggesting putting a Drupal field on an Indicia form - not that it couldn't be done but it is not something currently supported.
You could use a Drupal user field assuming you are asking users to register. They could complete the tick box at registration and they could alter it in the future by editing their profile.
The Indicia Person Entry form might also allow something similar. It's description is "A data entry form allowing people to be entered directly into the person table without needing a drupal account. An example use might be for people wishing to register interest in events without needing a formal account."
If you want the tick box on the recording form you could fudge it with an Indicia sample attribute, although it might be confusing to extract if someone is submitting many samples.
Another alternative would be to redirect after successfully entering an Indicia record to a Drupal form which would gather data to be stored in Drupal. With a bit of styling it might be seamless.
Alternatively, how do you feel about trying a bit of development yourself to allow you to achieve what you first thought? It might not be too hard to extend the existing form.
Jim Bacon.