Can we use Form2 resin in Form1+ tray?

My local Formlabs supplier has only Form2 cartridges and not the Form1 bottles. Do you know if its possible to open the cartridge in order to use the resin? How can I do that, is it simple?

Yes; just unscrew the vent cap and pour. And of course make sure that the resin version is supported on the Form 1+. You can check that in PreForm.