curl --request PATCH \
  --url https://sandbox.withclasp.com/beneficiary_allocations/{public_id} \
  --header 'Content-Type: application/json' \
  --data '
{
  "member": "<string>",
  "allocation_type": "<unknown>",
  "splits": [
    {
      "beneficiary": "<string>",
      "percentage": 50
    }
  ]
}
'

{
  "id": "<string>",
  "member": "<string>",
  "allocation_type": "<unknown>",
  "splits": [
    {
      "beneficiary": "<string>",
      "percentage": 50
    }
  ]
}