For A and B level races competitors need to comply to a few rules so that they can compete – 

• They need to be members of their national rafting organisation.
• They can only represent one country in any one year.
• If their passport is not the same as the country they race for they must prove to their national organisation and then the IRF that they are permanent residents of that country.
• They need to have proof of their citizenship or residency to show at the event in case they are asked for it.

Reserves at A, B, C and D level races – 

• Only one reserve is allowed per team.
• Only that reserve can be substituted into that team.
• During the event the reserve can be substituted in when needed BUT ….
• No substitutions may be made during a single discipline. So if the reserve is used for Heat 1 in the Slalom – then they must be used for Heat 2 as well. And the same goes for H2H – the SAME 6 (or 4) paddlers must race in each heat of the H2H.

So its fine to use your specialist slalom paddler for Slalom and then replace them with your downriver specialist for Downriver, but changing the paddlers between heats is not allowed and can lead to your teams disqualification.