For search terms/keywords, I'd add all three. Looking at your current manufacturer's pages I'd also have the Agilent, HP, and Keysight links all go the the same page.
It can't really hurt for you to have all three tabs/links, but maybe put a little blurb about the name changes on the landing pages for those tabs.
For product searches like DSOX2024A I'd expect to land at a specific product page, not necessarily a "manufacturer" page. Feel free to contact me outside of this thread if you'd like to discuss further!.