This is a subject that's been mentioned before but examples keep cropping up...If you acquire an item with one or more vintage signatures on it and want to complete it with modern signatures via signing events I would strongly advise against adding extra inscriptions such as mission names, assignments, dates etc, unless the vintage signatures already have them.
For example if you have a nice photo from the Apollo 11 mission which has been signed by Armstrong and you want to add Collins and Aldrin it may be tempting to have them add "Apollo 11 LMP" and "Apollo XI CMP" after their names but it just looks completely out of place on a crew signed item.
Here's an example from the latest RRAuction.
It's still a great signed piece but, at least in my opinion, it would have looked much neater without the Apollo 11 inscriptions after the Aldrin and Collins signatures.
They would never have signed like that back in 1969, especially not on a picture from Apollo 11, signed only by Apollo 11 crew members, and with the words Apollo 11 printed boldly across the top of the item. Having them each add Apollo 11 as well just looks daft.
At least this one hasn't gone the whole hog and had Aldrin add "MAGNIFICENT DESOLATION" across it in silver pen.
Sometimes less really is more.