I find that EN19 is usually used for its strength and not its creep resistance, therefore this method normally fits the bill.
Usually recommend E312 type (29Cr 9Ni). First preheat the EN19 to 250oC then weld at least 2 butter layers of 312 to the surfaces to be welded. Slow cool. Then weld the surfaces together with the 312, no preheat.
Restrictions: If the joint is to be subjected to heat over 300 oC the 312 will start to go brittle.
If the joint is over 40mm thick the welding should be done with a 308L (not the buttering)
This is the belt and braces method. I have known it welded with an E7018 without preheat but you are on a wing and a prayer.