Forum:Tualatin and nova summoner

If I have nova summoner and shining angel at the start of the phase, can i use tualatin's effect if those two die but I still special summon with their effect? Because the effect states that if i have two or more at the start and if THEY(the ones at the start, not the newly summoned ones) were destroyed. Also does tualatin's effect only work by this effect, meaning no valhalla? Thank you!!!