I use velcro black for roos and white for pullets. Each leg band gets a color for relationship (brother sisters get same color) I just use a pipe cleaner and wrap that around the velcro. I then use a color for each bird so that is the real ID. So each bird will have a family color and an individual color. You can use in combination that would work for you. I have some birds that will just have one color since I don't know family or need it. All hatchlings will get them and be banded for parentage and individuals.
They are easy to adjust as they grow if you make the velcro big enough. May have to change them midway if you make it too small. Cheap, easy, lots of options with colors (I don't use red) and visual.
just make sure you don't leave anything sharp pointing from the pipe cleaners and I put the twisted part to the outside so they are not irritated by it.