To add a member from a previous marriage, go to the members link and click "Add new member". Enter the information for the person and select the former spouse in the relationship section. Check the "Divorced" checkbox.
To add children from previous marriages, add the parents first. Then add the children and select the parents accordingly in the relationship section.
The family tree will be generated to show the member for every marriage and the children will be linked with the correct parents.
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How do I add a member or children from a previous marri... - 
