Suppose I have the following code and I want to show them in the same picture.

figure1=Plot[x,{x,0,1}];

figure2=Plot[2x,{x,0,1},epilog->circle[]];

some missing line(when this line is uncommented, it removes epilog in figure 2)

figure3=Plot[3x,{x,0,1},epilog->Triangle[]];

figure4=Plot[4x,{x,0,1},epilog->Line[{{0, 0}, {1, 1}}]];

Show[figure1,...,figure4]

1.I want to put all plot options outside 'Show[]', as this facilitates commenting/uncommenting part of the code for various uses. But 'show' only fully respects the 1st argument. How to keep all plot options in each of these figures intact?

2.How to fill that missing line?

Suppose I have the following code and I want to show them in the same picture.

figure1 = Plot[x, {x,0,1}];

figure2 = Plot[2x, {x,0,1}, Epilog->Circle[]];

(* * some missing line* *)
(* when this line is uncommented, it removes epilog in figure 2 *)

figure3 = Plot[3x, {x,0,1}, Epilog->Triangle[]];

figure4 = Plot[4x, {x,0,1}, Epilog->Line[{{0, 0}, {1, 1}}]];

Show[figure1, figure2, figure3, figure4]

1.I want to put all plot options outside Show[], as this facilitates commenting/uncommenting part of the code for various uses. But Show only fully respects the 1st argument. How to keep all plot options in each of these figures intact?

2.How to fill that missing line?

figure=Plot[x,{x,0,1}];

The above is the preceding code. How to add the following info sequentially to this existing 'figure'? Rather than putting these features all together, this facilitates commenting/uncommenting part of the code for various uses.

1.an epilog

2.a line

Suppose I have the following code and I want to show them in the same picture.

figure1=Plot[x,{x,0,1}];

figure2=Plot[2x,{x,0,1},epilog->circle[]];

some missing line(when this line is uncommented, it removes epilog in figure 2)

figure3=Plot[3x,{x,0,1},epilog->Triangle[]];

figure4=Plot[4x,{x,0,1},epilog->Line[{{0, 0}, {1, 1}}]];

Show[figure1,...,figure4]

1.I want to put all plot options outside 'Show[]', as this facilitates commenting/uncommenting part of the code for various uses. But 'show' only fully respects the 1st argument. How to keep all plot options in each of these figures intact?

2.How to fill that missing line?