Could Fan Charts use filters?
Say that there was an example of extreme pedigree collapse and a graphic illustration would help clarify… where the common ancestors were filled in on the fan chart. So a fan chart with ONLY the common ancestors filled in would help understand the collapse. (Or maybe an option to apply color to only those common ancestors.)
A split screen option would be possible if the Fan Charts Gramplet allowed the same features but also had an Active Person/Home Person switch. So a Relationship path between <persons> filter simultaneously apply to the fan chart & Gramplet would show the paths from common ancestors. If they were double (or triple cousins, this also could be graphically represented.
Filtered charts could also allow special condition to be illustrated. Like an arc of great-great-grandparents without any of their descendants or ancestors. Or a fan chart that only includes grandparents & up - the blank center of the graph allows it to be re-used for all the sibs & their descendants.