Since it is a weekend, I have taken the time to let FTM run an Extended Family Chart on a fifth cousin of my mother and see how far it will go.
I have 65,000 peeople in my file. Most are related to me in one way or another, except for maybe 100 lines or family groups that I haven't been able to tie into my Surname Study yet - but I am entering people with that surname wherever I find them.
So, I started with
Unchecked - "Include everybody in this file in right panel"
ie DON'T include everybody in this file.
1 generation of ancestors and 1 generation of descendants.
I was getting small results up through 3 generations. It generated fairly quickly with maybe 50 people or so by the third generation.
I then went to four generations of ancestors and 4 generations of descendants.
The report took somewhere in the neighborhood of a half hour to generate. I decided to quit there as I didn't know how much longer it might get if I added more generations.
The report now has 59,748 people in the report. The report is 3,592 pages long with 8.5x11 paper. I can't shrink it smaller, or it would be unreadable.
You can find how many people are in a chart by:
Right click - select all
Right click - export. At that screen, click the "SELECT BUTTON. That will show the number of people at the bottom of the right panel = 59,748.
I find myself by looking me up in the People Locator in the right side. There am in in the middle of the "island" for my surname.
Next to my box is my ex-wife, with number 5710 in the upper left of her box. I find her in the People Locator box and discover that she is in the report twice - which I already knew, because she had an identifying number in the upper left of her box. I select the second instance and jump to about the middle of the report (well over 1,000 pages) and find her in her family's island tree. (Although divorced, she is the mother of my children and grandmother of my grandchildren, so I have traced her genealogy.)
By the way, the number 5276 means the report has generated 5,276 "islands" so far at that point. This is not "islands" in the context of orphan records - but in the context of separate groups of people connected by blood only within this report.)
Back to the original posters question - how else can these two islands be connected other than by using this common number for the various instances a person has in this report.
Colors and lines would simply just be confusing and would just serve to make the report more unreadable. A person would run out of basic colors before getting into shades very quickly. Using lines would completely obliterate the report. Consider the first instance of my ex-wife is over 1,000 pages from her second instance. A single line to travel over 1,000 pages? And how many other lines would be on the intervening pages. In turn, I have traced my ex's mother's family. Her mother is in the "island" where my ex is a second time with the number 5276 in the upper left. This, in turn, is the key of a another island where her surname family will be in this report - approximately 500 pages further down in the report.
I'm sure FTM would be interested to know if there is a better answer, I know I would.
This report is basically for use a filter to identify everyone related to a certain person by blood or marriage for file manipulation (by either exporting or deleting people). It's use as a report to actually print on paper is rather limited.