If I understand @hoverfrog's directions, if both Alandri and Kaikara make checks, then we would have to split up. If that's the case, then Thandeka will go with Kaikara and will assist her. However, unless Silas and/or Alandri have spells that will allow the two groups to communicate to each other from a distance, I would suggest we stay in one group. I can only say that Thandeka doesn't have any spells that will help coordinate the two groups.
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If I understand @hoverfrog's directions, if both Alandri and Kaikara make checks, then we would have to split up. If that's the case, then Thandeka will go with Kaikara and will assist her. However, unless Silas and/or Alandri can communicate to each other from a distance, I would suggest we stay in one group.