Hi,
Maybe you ca use 'conditional compilation'.
1. Create a Visual Studio project for AutoCAD referencing AutoCAD assemblies with, at the top of each file (class):
#if ACAD
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.Runtime;
#endif
using Bricscad.DatabaseServices;
using Bricscad.EditorInput;
using Bricscad.Geometry;
using Bricscad.Runtime;
2. Add to your project properties, in the Build tab, the Conditional compilation symbol: ACAD
3. In the same solution, create a new project referencing Bricscad assemblies.
4. Right click on the Bricscad project in the solution explorer > Add > Existing element. Select all the files (classes) from the AutoCAD project folder and change the Add button in the bottom of the dialog to Add as Link.
5. Try to compile...
This way, every changes to the AutoCAD project code will affect the Bricscad project.
PS: I'm not certain about the Visual Studio UI translation.