Of course, but you must admit that you are not using the game's definition of "surprise". Why would anyone expect you to follow the rules about when it ends?
I disagree, the word surprise has a meaning... to not see something coming, to be taken by surprise... the game ADDs 'if in the first round of combat.... no where does page 189 (the only surprise rules I can find) say "Ignore what the word surprise means in every day language and instead make it a term that only ever means in the first round of combat"... so yes, you can surprise someone when you do something surprising...
I really don't understand how it is possible to read the word surprise, and not think it means surprise...
Just like when someone said person A can't surprise you if you know person B is there.... or to put this in a very easy to understand analogy, if my girlfriend walks up to you and says "I need help I'm lost, can you show me on my phone's map where we are?" and I am hiding near by, when you look at the phone to help I can't jump out and surprise you with a knife... after all you knew she was there, she isn't surprising you... and according to you guys if two people are working togather they can't set up for one to surprise the target unless they both do...
back to the three round assassin feast that actually happened in my game... the Drow attacked the wizard with assassinate (auto crit, sneak attack and did like 90% of the wizards HP in one hit) the PC bard assassin broke invisibility and hit the drow with an assassinate (autocrat sneak attack) round 2 the drow turned on the PC and hit with 2 attacks for almost no damage, the wizard readied and action to disengage after the PC went, then the PC hit the drow with sneak attack (Another enemy adjacent...aka npc wizard) then wizard backed off round 3 the drow hit the PC 2 more times, then the wizard cast magic missle, then moved back into melee, then the PC killed the drow with a sneak attack...
end result was the plan worked... and My group even after this thread was mentioned still belive we are playing by the rules....