Hi Valentin,
I have created service and done redifintion of the define method in *MPC_EXT Class and included a statement.
lo_entity_type->ADD_AUTO_EXPAND_INCLUDE( iv_include_name = '<yourAbap Structure name>'
iv_bind_conversions = 'X' ).
Now without changing the properties, my Model has been appended in the service.
Please let me know if have any queries.
Thanking you
Vengaiah