Basic ship design upgrades

Is there a straightforward way of using an existing ship design, but upgrading certain elements in-place, without having to play with the Legos again?  For example, suppose that I'm basically happy with the star fury that I've got, but I want to beef up its engines to my most recent tech?  Is there an easy way of doing in-place engine replacement?

Or suppose that through advances in miniaturization, I now have room to throw on some extras, in addition to my base design.  Is there a way of pulling up a completed design (not an empty template), and just adding on an item or two?

Thanks!