Hi Colin,
I think I can explain what is happening and a partial workaround.
You are mistaken in saying the Witness ‘facts’ are attached to both Marriage sources.
Those two sources 5. and 6. are attached to the Name fields of William and Hannah as indicated by the small superscripts 5 and 6 after their names.
There are no superscripts on the Witness ‘facts’ so they have no attached sources.
In Family Group Sheets the Family Members (Husband, Wife, & Children) only show Individual facts, so Family facts like Marriage are omitted.
See Report > Options > Contents tab, Family Member Events/Attributes that are all Individual facts.
Interestingly, the Fact Witnesses attached to Family facts like Marriage are included (which seems inconsistent).
Family facts like Marriage are only shown in the summary at the top of the report for the Husband & Wife (not the Children).
See Report > Options > Contents tab, Family Events/Attributes (Family Summary) that are all Family facts.
It is possible to include Marriage facts in the Family Member Main Items for everyone (Husband, Wife, & Children).
See Report > Options > Contents tab, Family Member Main Items.
Use Add… to include a Marriage item %INDI.FAMS>MARR%
That will appear for everyone (Husband, Wife, & Children) who has a Marriage fact.
For the Husband & Wife, it repeats the Marriage entry in the summary at the top of the report (that can be excluded if you wish).
The snag is that when anyone has more than one family partnership it only shows the 1st partnership Marriage (if it exists).
That may not be the Marriage for the people shown in the report.
I suggest you report the problem to Calico Pie.
Point out the inconsistency of showing the Fact Witness for the Marriage but omitting the Marriage event itself for the Children.
It would seem useful to have an option to include any of the Family facts for the Children.
Regards, Mike Tate