How to word an invite so people know it's not a surprise!

[Thisismynewname123]

We're making a party for my mum's 70th birthday. I want to word the invitation so that people know that it's NOT a surprise party, as otherwise people are unsure whether they can mention something or not. Any suggestions on the wording?

Mum is looking forward to seeing you? Why would everyone assume it's a surprise though?

I'd never assume a party was a surprise unless it specifically said so

How about 'Thisismynewname and Thisismynewname's Mum look forward to welcoming you to a party, to celebrate Thisismynewnames Mum's 70th birthday, on ... '

We sent out a save the date a few weeks ago, and have had people saying they weren't sure if it was a surprise. So want to make it clear on the invite

I would have thought the assumption is that it's not a surprise unless you say it is?

Something along the lines of "Mum would like you to join her for a party in celebration of her 70th birthday" should be fairly clear.