Currently you can either pay a ‘youth fee’ or an ‘adult fee’. I would like it to be changed sometimes. Eg: If a sibling comes to an event and a scout comes to an event, they are both Youths, but their costs are sometimes different. This is confusing for the Parents registering.
This is actually possible now, you can use the Event Items Available for Purchase and add a Sibling option there with a separate price.