When an oblique shock forms, what happens to the normal shock that helped it form?

What happens to the normal shock that helped the oblique shock form, in the first shock of a lambda shock? Oblique shock waves form because :

"An oblique shock wave is a shock wave that, unlike a normal shock, is inclined with respect to the incident upstream flow direction. It will occur when a supersonic flow encounters a corner that effectively turns the flow into itself and compresses." - Wikipedia.

(Over this whole question, I'm referring to the first shock in a lambda shock, just to make an example)

For the oblique shock to form, there has to be a normal shock first, I think. The normal shock makes a separation bubble which makes the flow turn, making an oblique shock. My question is, what happens to that normal shock when the oblique shock forms? Does it disappear? If so, why? This answer and its comments has some really good info, but (for me) it didn't explain this part.

Also, if the flow behind a normal shock is always subsonic, how would the oblique shock form? I thought flow had to be supersonic to form an oblique shock?

• @ROIMaison Thanks for the link, but it doesn’t really talk about how the oblique shock I was asking about forms, unless I missed something. Feb 13 at 15:57
• The way I read it, initially there is a normal shock, which disrupts the flow and causes separation. This separation bubble presents an obstacle to the flow, which means it needs to generate an oblique shock to get around it. Feb 13 at 16:11
• @ROIMaison That’s actually how I thought of it too, but my question was what happens to that initial normal shock? Feb 13 at 16:13
• @ROIMaison (what happens to it when the oblique shock is formed of course) Feb 13 at 19:16