Custom backgrounds with expanded spell lists?

[stewstew5]

In the phb there is a rule next to backgrounds to facilitate custom backgrounds that lets you choose two skills, two tools, and a feature from another background OR working with your DM to make your own. Is there any such rule in Guildmaster's Guide to Ravnica for backgrounds with expanded spell lists?

[Undyne]

In the phb there is a rule next to backgrounds to facilitate custom backgrounds that lets you choose two skills, two tools, and a feature from another background OR working with your DM to make your own. Is there any such rule in Guildmaster's Guide to Ravnica for backgrounds with expanded spell lists?

Sadly, no... I wish there was one. I've tried and I always scrap it in fear of the spells in combination were too strong. That's just my paranoia with my own homebrewing, though.