I2C on Rockpi4 overlay

Hi All. I have installed the latest version of DietPi on a Rockpi4.
When I run I2cdetect I can read from bus 0,1,3 and 4 but bus 7 does not exist. This would be SDA pin 3 and SCL pin 5.
I am guessing that I have to add a reference to an overlay but I am unsure how to do this with the RockPi. You would add it in config.txt for the Rpi but that doesn’t exist with the RockPi. Can I get some help with this please?

I2C7 on the rockpi works out of the box on the with Debian10.

Cheers

I found a solution by adding the following to the open /boot/armbianEnv.txt
overlays=i2c7

Cheers