The 'Suits' actor said part of what the pair hope to accomplish through their advocacy is to emphasise that "we all know what it feels like to have our feelings hurt."
The target of her lawsuit, Associated Newspapers Ltd, argues that the principle of open justice "The public's right to know" means the friends should be identified.
The former American actress was seeking damages from Associated Newspapers Ltd for alleged misuse of private information, copyright infringement and breach of the Data Protection Act.
Meghan Markle and son Archie have been living on Vancouver Island, Canada since the beginning of January 2020, while Prince Harry arrived at the end of January.
Some indications that Harry may also be flying to Canada to join Meghan, who flew there on Thursday to be with their eight-month-old son Archie.
It is traditional to give royal sons titles reflecting the three historic realms -- England, Scotland and Ireland -- that made up the United Kingdom.