Reply to email in thread folder using IMAP id goes to that folder+Sent but BCC does not go to inbox.

Using the latest MS maintained version of an Office 365 subscription:

Replying to a message that is in a folder of a .pst file for the thread discussions, having selected the message in the folder.
That message came in via an IMAP gmail account, and the reply is going to another id using the email id that the original was received from.

CC is set to get associated staff informed of the conversation.

BCC is set so the reply will be automatically recorded in the inbox, and so forwarded to an email archive id.
The reply gets posted:
Into the folder from which the original message was selected for the reply.

Into the Sent folder of the account used as the "From" for the reply.
To the indicated "To" id.

To the indicated "CC" id.

BUT not to the inbox of the specified BCC id.

Settings for sent emails are ticked for the SENT folder, and ticked for the Storage folder of the message being replied to.

Basic concept -

Messages in inbox (IMAP) - for action (with auto forward to the archive id)

Messages grouped as conversation threads (a .pst on the PC ) of the project.

Messages sent, are also posted (via the BCC) into the archive IMAP account where they are held as backup record.

So - can anyone detail how Outlook may be set to actually post the BCC, or is it show the received Blind Copy ?