Second I could use the narrow gimp that I'm using on the inner border. With this option they will read more as one piece.
My third option is to butt them together with no division at all. But even though they are the same theme, fabric etc. there is a definite line and shouts that's they are two separate pieces
Since I mentioned on Viv's piece how little it takes to fool the eye, with the magic of Photoshop I will show how I could make that visual division disappear..
By fiddling with the lace at the top of the seam line first... I know I have more or could easily replace what's there. Then I could extend branches and leaves from one block to the other... Finally I could find another medium sized heart to put on the seam at the bottom... Just three things..and the line would disappear. Ruby asked: "Am I correct in understanding that it is important to select which block has the most elements to travel over? To ONLY bring elements from one direction. Or with some blocks the extensions could come from both sides?" It really doesn't matter where you bring the elements from ...(you can even add new elements) ...the important thing is interrupting the line...The straight seam "before" on the left and after 3 simple additions on the right... The two blocks would now "read" as one.
All three of these options are perfectly viable with none being really better than another...it's a matter of personal choice.
You're certainly welcome to comment here with opinions on these options... Since I already made my choice and finished this morning it is a moot questionfor me but you can guess which I chose...
While stitching early this morning I saw a tiny mouse scurry out from under the china cabinet and scurry right back... I put a piece of cheese on an old-fashioned mouse trap and slipped it under there... Morris KNOWS there is food under there just out of his reach and it is driving him crazy...