How to copy boundary types from a volScalarField?
 

Hi all,
I am trying to create a library that solves for several volScalarFields (say M0,M1...).
The problem is described in terms of the transport equations for the fields, and internally I want to do a transformation such as
and then solve the transport equations in terms of theta.
What I would want is that the application using the library will provide the initial/boundary conditions on M0, and that will be converted to equivalent boundary conditions for theta.
I see how the internalField values can be initialized, but how do I convert the boundary conditions?