How would I leave one Vector4 value intact while replacing the rest?

Questions & Answers
1

Something along the lines of:

Vector4 initV4 = new Vector4 (1,1,1,1);
Vector4 addedV4 = new Vector4(3,2,5,9);
initV4 = new Vector4(addedV4.x, leavethesame, leavethesame, leavethesame);
2

intvV4 = new Vector4(addedV4.x, initV4.y, initV4.z, initV4.w);