This is a double-whammy, you need to avert both the russian revolution and WW1... I believe in you AH.com.
Rules:
-POD must be post-1880, I know it's the post-1900 forum, but you can go a little back. All the interesting stuff will happen in the 1900s.
-Please make the cousins be semi-friendly at least sometimes, who doesn't want prince and princess political marriage stories but with nukes?
-Try to keep as many other monarchies around, especially japan, lets get Hirohito hitched to a nice european princess. Keep the kings of italy and spain stronk too. Interracial royal marriage on the millenium for Ethiopia?
-The more power the kings and queens have, the better. Parliament can stuff it, lets get a clever king to lead england to victory!