Hi, there's a thread for part of this here
same sex union
To support Heidi in the setting, promote equality & inclusion it's important that others have appropriate information to base their responses on - the colleague may of made a wholly human, professionally inappropriate assumption that it was Heidi's nan, sharing information could happen by way of the enrolement process, as early as possible ask parents how they like to be addressed/what their child/ren call them at home, and then with permission share this information with colleagues as a priority.
It is unlawful to discriminate and if homophobia exists in any degree it would be useful to organise a meeting where staff can openly discuss their perspectives, sense of prejudice or discomfort in recognising same sex relationships in ways that help them to overcome those barriers.
If children share an observation using incorrect information such as 'Heidi's nanny is here' .. you can provide the correct names, where you know them to be true, by adding 'Heidi's mum is here', if or where challenged.. 'that's not Heidi's mum she came yesterday' you could expand with 'Heidi has two mums that look after her.' through this children may be prompted to explore diversity .. 'I have one mum why does Heidi have two mums?' which opens up the discussion on a child led footing where you can explain how 'everyone has different families' moving on maybe to discuss structures .. how some children have two dads, others have a mum, a grandpa and a bigger brother, some have a mum and a dad who don't live with each other anymore ..
Mommy, Mama and ME on amazon
Hth xx