Trying out Dorico. I understand the concept of master pages, frames, etc. The problem is when if I add page 3, insert a music frame, then unlock the frame from the master, the music from page 1 is copied to this frame. It is linked to the music on page 1 as if a delete a note on either page, it is also deleted on the other page. To explain it another way, if I change any frame to a layout frame, the music on page one is copied to that frame.
Dear Babe8,
I think you do not fully understand the way music frames work, especially the part related to links. You can check the manual, p148, but I don’t think it will help you here. John Barron had made a very useful video on the Youtube channel about that, you might check it, in order to master the subtleties of music frames !
Before making my post, I watched many of the videos and scoured the forum. Tried a bunch of different things. Thanks for the link to John’s video but it didn’t help. Why, when I unlink a frame from the master to have a layout frame, does the first page of the master copy to this newly created frame? I want a blank frame in order to show only the instruments needed.
I’m not sure I understand what you really want to do. If your aim is to select only some of the instruments, then why don’t you just create a new layout in Setup mode (right panel) where you select the instruments you want (check the squares on the left panel, with the new layout selected blue) ? Sorry if I mislead you, I am just trying to understand what you want to do to help you 
It’s tough to advise without knowing exactly what you want to accomplish. But if you have multiple flows, you can select which ones appear in a music frame in Engrave mode.
If you want a completely new independent Master Page, try creating a new Master Page Set. This interface is minimized by default and is located below the Master Pages interface in Engrave mode.
Like most orchestral scores, there are different instruments used on each page. If a frame is a layout frame, there is a dropdown to select which instruments are shown. Fantastic. Problem is that when I create a layout frame, the music from page 1 of the master is duplicated onto the layout frame. I attached a screen shot. Notice on page 3 the frame is labeled ‘LA’ and the music is a duplicate of what’s on page 1. I can change the instruments shown but if I delete the music, the music on page 1 is also deleted. If I chance to frame to ‘MA’, the page becomes a normal page 3 but I can’t change the instruments.
When you insert a layout frame the music starts from the beginning of the flow assigned to it. They are not meant for what you’re trying to achieve. Seems like you should check the ‘Hide Empty Staves’ options in the Vertical Spacing section of Layout Options.
Seems that Vilnai has understood what you were trying to do. 
Merry Christmas dear fellow Doricians!
Babe8, the reason that the first page of music appears again in a new page at the end of the layout when you unlink the frame at the start of the layout is that the ‘Default’ master page pair still has a music frame on it that wants all the music to appear: when you override the first page, Dorico assumes that it should keep showing all the music, but now it has to start on the second page. You could defeat this if you really wanted to by editing the ‘Default’ master page to remove the music frame on both left- and right-hand pages.
However, Jay is quite right: you need to use the options on the Vertical Spacing page of Layout Options.
Then what’s the purpose of layout frames?
Create complicated stuff like 4 hands scores (left page for left player - right page for right player) automatically…
Or snippets which show, in the Table, the first bars of each flow… We could go on like this with specific uses that were just impossible with other software to achieve
The problem is that when you unlink a page from a chain, whatever is on page 1 shows shows up on the new chain. So to use your example of a 4 hand piano, the left hand music will be on chain LA. I want to start a separate chain on the right side but when I unlink the page from LA, a new chain is created, (LB), but the music is copied from LA. And it’s a direct link. Change something on one page, the change is reflected on the second page.
Yes, but you’d probably want the same music on both pages, except you’d want to only have Piano 2 (Secondo) on the left page and only Piano 1 (Primo) on the right page.
Exactly. So how do I do this?
There is an example of that in the video I posted I think!
You choose which flow and which instrument shows on each frame and that’s it. The same music on each page to be played together, and page turns synced
Not sure it’s the right link up there… I meant this video : Layout Options, Chord Symbols and Small Solo Instrument Staffs | Discover Dorico with John Barron - YouTube
You use the players selection menu in the frame. Here’s a quick and dirty example. The LH page has a layout frame LA, with only Piano 1 selected, and the RH page has a layout frame LB, with only player 2 selected. Both start at mm 1, which is what you want, but only show their respective players.
Got it, thanks.