How can I insert another .scdoc in my active scdoc similar to the insert file option under the assembly tab in Space Claim in C#
You can add a reference:
using ScdmScripting = SpaceClaim.Api.V17.Scripting;
Then you can use
string path = "C:\test\test.scdoc"; ScdmScripting.Commands.DocumentInsert.Execute(path);