Usually, an instructor will not take out a group with a mixture of skiers and snowboarders, especially for beginners and intermediates. This is for various reasons such as the difficulty of being able to teach mixed disciplines, and their insurance may not cover them.
While it is very rare, if you are planning on booking a guide for the day, they might be willing to take out snowboarders in their group too. It will depend on the individual instructor or what the ski school permits them to do.
If you are unsure whether the provider you want will allow this, then please get in touch,