Allow creation of child participant #4277

Added a link to the relationships tab to create a child participant.
(cherry picked from commit 87e8f57f7968ae8858e530937dec67852d2bf7a1)
(cherry picked from commit 3900b8e671d9641e0a6353008f8418988b3e92b5)
Explaination of relationship code #4277
(cherry picked from commit 2f4cfd491680f0a79d322c1cb6189fc2477b1f1f)
(cherry picked from commit 1bec6e8d8d844307faa9b1a0518f11c8a9932ba1)