Create a new broadcast group, optionally with its first members.

Before you call

• name is required and must not match an existing group's name.
• members is optional. Each member needs a phone with country code; name is optional.

How it works

• Members are saved as customers. Those already in your account are reused.
• The response has groupData (groupId, memberCount, groupChatName) and invalidMembers.
• Numbers that cannot be parsed are returned in invalidMembers. If every number is invalid, the request fails.
• Demo accounts have a cap on groups and members; members over the cap come back in invalidMembers.