A bride-to-be, believed to be from America, took to Facebook seeking advice after discovering her fiancé's 16-year-old son had got her 15-year-old daughter pregnant.
The anonymous woman revealed it was five days before their nuptials and questioned whether or not they should still go ahead.
Explaining that she and her fiancé have been engaged and planning their wedding for a year, the woman wrote: 'He has a 16-year-old son and I have a 15-year-old daughter.
'Two months ago we moved in together, so now we are a blended family.
'We are now five days away from the wedding. Yesterday my 15-year-old daughter and his 16-year-old son told both of us that she's pregnant. Edit: And he's the daddy.
She concluded the post with 'now what?', asking if she should still get married.
Her original Facebook announcement evoked 50 reactions and 70 comments, before it was grabbed and shared on the group That's it I'm wedding shaming.
There it notched up more than a thousand comments and reactions - and perhaps unsurprisingly, many weren't particularly sympathetic.
A number of group members likened it to a situation in Teen Mom, where teenage sweethearts Tyler Baltierra and Catelynn Lowell became step-siblings after their parents got together.
One joked: 'Oh you're gonna be a blended family now... That's a certainty!'
Another commented: 'Oh God what a mess and what a fun situation to explain to people in the future.'
And one wrote: 'Obviously they are not related but that doesn't make it fine. The family dynamics and relationship structures have changed. It's a lot for kids to deal with. Separate the kids. Get some family therapy.'
But several did relate to the bride-to-be's difficult situation, with some sharing their own similar experiences.
'This actually happened with a girl I went to school with, their parents did still get married and now the kids are engaged and have two kids,' one member commented.
Another revealed: 'My parents married and then years later my mom's mom married my dad's dad, making them step-siblings, my brothers my cousins and my grandparents my double grandparents. The situation for me isn't weird if they didn't spend time together as younger siblings.'
And one pointed out: 'They're not related FFS!' while one urged them to still marry but 'maybe not adopt each others kids,' adding: 'What a mess indeed.'