Office 365 Shared Calendar

the only way this would work since the other users are outside the exchange organization, would be to publish the calender in office 365 to the internet then the users would be able to connect the generated URL.  link below explains in detail how to accomplish this.

http://office.microsoft.com/en-us/outlook-help/manage-and-preview-calendars-published-with-the-outlook-calendar-publishing-service-HA010388759.aspx

I can publish it, and send a link to the non-O365 offices to view.... but I don't think they will be able to edit the actual calendar, just a copy they open.

Assistants at each location need to be able to edit the calendar too.

Maybe if They purchase another O365 box for the company that already has o365... name it calendar, share the boss's calendar to it, and shortcut OWA to the other 3 offices?

There is only 1 exchange organization, so trust is not revelant.

Publishing the calendar does not solve the problem, as the non-exchange offices can not edit the calendar.

I was just spit-balling on my last comment... that the office who currently is on O365 could purchase another mailbox, called calendar@theirfirm.com

Share the bosses O365 calendar to that account.

Then let the 3 (Non O365) office access that calendar account via OWA to edit his calendar.

He'd only have one calendar, that all the office's would be able to edit. No more duplicate entries from syncing 4 seperate calendars at 4 offices.

Pretty sure this is my solution, now that I've had a bit to think about it.

Actually, I either didn't explain the issue well, or you did not understand the problem (as your first suggetstion would not work, and your second suggestion was just saying that your first suggestion would'nt work)

Regardless, you're the only one who responded, so you get the points.

Thanks.

There was not actually any accepted solution, but the points got to go somewhere.

you gave me a C because what you want to do was not possible.  and I explained why it wasn't possible.  of course if they purchase a mailbox in the "SAME EXCHANGE ORGANIZATION" then it will work but that's not what you asked.  You asked if they could edit it outside the organization and they can not.  I deserve an A for that.

I requested suggestions to get the boss on a calendar that is assistants in each office could share. I supplied that sharing the calendar might not be possible to non o365 users.

You replied that I should publish the calendar to fix the problem.... but that only allows the remote office to view. It was stated they need to edit as well in the original post. So your first post was no help.

I then suggested that I was going to create a generic user in the current o365 account, and use it just for share the bosses calendar to the remote offices. (this should be the accepted answer, but I cant award points to myself)

You replied that they need to be either in the same exchange org, or trusted org.
(the post that was in reply to was already suggesting a new account in the same o365... so explaining that it needs to be in the same exchange org.... after I just said I was going to create a new account in the same exchange org is irrelevant.

Finally you said I wanted to do something that was impossible, which leads me to be firmly committed to the fact that either I did not communicate the question well, or you simply misunderstood the spirit of the original post.
Since I have created the new account, already shared the calendar, and accomplished the task I was asking for suggestions to. I can say with certainty, I did not want to accomplish the impossible.

In the end, I came up with my own solution. Had either of your posts contributed in the slightest to the final solution... you would have received an A+.

you didn't accomplish the impossible because you did not accomplish it.  you wanted to share a calender with edit permissions to people outside the organization and guess what you didn't do that.  if your intention was to share a calender with someone in your organization then you did that.  by right clicking on a calender and sharing it with another user in the organization you completely came up with that complex solution on your own.  but that wasn't your question.

"I am thinking about sharing his Office365 calendar to users in the other 3 companies. But not sure if they will be able to edit it"  

To this I said "NO YOU CANT" and you did exactly what i said by adding the user to the exchange organization.  But yes, its your solution