how replace a component without changing the mates

hi!
i have created an assembly but i want to replace some components.this components have the same dimensions than the others butdifferent name. but when i replace it, the mates aren´tupdate. and i want to maintain the same mates.
what can i do?
thanks!

p.d. i can change the dimensions of the replacementcomponents.SolidworksAssemblies