Will Simple Title Case or Intelligent Title case work for entries such as MacDonald?
The tools we offer of Simple vs Intelligent Title Case have limitations when it comes to names. Our software is global and the spelling of names is going to vary greatly depending on the region, so what may work in one area, may not work well in another. The Intelligent title case option would better suite fields such as Titles or Departments.
As far as names go, there isn't a way to restrict the letters to be all lower case with respect to the specific letters in the middle of a string.
The challenge is also the same for names with apostrophes such as O'Donald, names with hyphens such as Smith-Jones, and the list goes on, especially once you get into other regions.
You may consider a tooltip, either in the field's Data Capture tab, or as part of an Entry Block's instructions stating "please do not use all capital letters"