Combining chart for comparison got error

I used the code below to combine two figures as attached for comparison. The charts are extracted from the long code attached by changing the input between C=0 and C=1.

The charts:

The comparion lines:

if true
fig = figure(6);
ax = axes(fig);
xlabel('\xi');
ylabel(' \lambda(\xi,\tau)');
title('Comparions for the case K=1');
h1 = openfig('C0K1.fig','reuse');
h2 = openfig('C1K1.fig','reuse');
copyobj(h1.Children.Children,ax);
copyobj(h2.Children.Children,ax);
close(h1);
close(h2);
savefig('K1compare');
end
hold on
legend('C=0','C=1','location', 'northeast')

Error showed:

Error using copyobj
Too many input arguments.
Error in K1compare (line 9)
copyobj(h1.Children.Children,ax);

How to fix please?

Answer 1

[dpb]

h1.Children.Children returns a comma-separated list--

>> h1.Children.Children
ans = 
  0×0 empty GraphicsPlaceholder array.
ans = 
  2×1 Line array:

  Line    ( \lambda_u = 16.0623)
  Line    ( Classical P3D)
>> 

You can let the empty placeholder be passed by

opyobj([h1.Children.Children,ax]);
copyobj([h2.Children.Children,ax]);

More robust would be to use findobj to only return and copy the lines.

[Hai Nguyen]

I tried the new lines below as instructed but still got error.

if true
fig = figure(6);
ax = axes(fig);
xlabel('\xi');
ylabel(' \lambda(\xi,\tau)');
title('Comparions for the case K=1');
h1 = openfig('C0K1.fig','reuse');
h2 = openfig('C1K1.fig','reuse');
copyobj([h1.Children.Children,ax]);
copyobj([h2.Children.Children,ax]);
close(h1);
close(h2);
savefig('K1compare');
end
hold on
legend('C=0','C=1','location', 'northeast')

[Hai Nguyen]

https://www.mathworks.com/matlabcentral/answers/764406-merge-saved-figures-into-one-figure-in-the-same-plot?s_tid=answers_rc1-2_p2_MLT

This link solved a similar problem. I tried and it worked for my case.