Some feedback on your test code.
hFigIAxes = findobj('Parent',figT,'Type','axes');
No need to do this. You already have the axes handle, FigTile1 which is the same as hFigIAxes.
copyobj(FigTile2,hFigIAxes)
Here you are copying the first axes to the second axes but axes cannot be a child of another axes. I think what you meant to do is to copy the children of the first axes to the second axes:
copyobj(FigTile1.Children, FigTile2)
The result would look like this. Then, you can add the additional steps of adjusting the axes limits.
A= rand(50,1)*10;
B= rand(5,1)*length(A);
figT=tiledlayout(2,1);
FigTile1= nexttile(1);
figA = plot(A); hold on;
for i=1:length(B)
xline(B(i),'r')
end
FigTile2 = nexttile(2);
copyobj(FigTile1.Children, FigTile2)
box(FigTile2, 'on')
I can point you to other solutions to adding a magnifier axes in case you are interested. There are many more, these are the ones I'm familiar with.
