Consider the following expression:

expr = Hold[
   {
    f[
     {1, {Print@1}}
     ],
    g[
     {{{Print@1}}}
     ]
    }
   ];

I'm looking for a way to apply a replacement rule to the contents of all expressions with head f. To give a more concrete example, let's say I want to replace Print by Echo, but only inside f.

Restrictions: I have no knowledge about the exact structure around and inside f - there could be more or less nesting going on. This means the replacement rule can't capture the wrapper with Hold attribute, nor can it capture the individual parts of f[…]. (And the evaluation of Print should be prevented of course)