True Stike plus a +2 weapon

I have the spell True Strike and I have a +2 scimitar on my character that they are proficient in

• I tried Override the Ability Score used and damage dice on the weapon. DnD beyond wouldn't let me do that
• I tried making a custom weapon. Dnd Beyond doesn't let me add the +2 magic bonus, or the addional d6 damage die from being level 5
• I tried modifying the Cantrip itself. DnD beyond doesn't let me add an attack roll to it

What do I do?

Customize the +2 weapon stats and roll the additional damage die separately.  You can make the additional damage into a custom attack to keep it on the front page.

There is currently no way to get a single action on the character sheet to properly implement True Strike.

You can sort of muddle through with one action for the attack and one for the damage roll, but only if your weapon uses a d6 damage die.

I've tried several different approaches and I ended up giving up and just using physical dice.