%%%%%%%%%%%%%%%%%%%%%%%%
input boxes;

midhsep:=3cm;
hsepf:=1cm;

vardef sepfamMid (suffix a,b) :=
    a.e=b.w-(midhsep,0);
enddef;

vardef lesboites (text t) :=
  forsuffixes $=t :
    boxit.$(str $);
  endfor;
enddef;

beginfig(1);
  lesboites(david,sarah,yann,elsa);
  elsa.e-david.w=yann.e-sarah.w=-(hsepf,0);
  sepfamMid(david,yann);
  %%
  %%drawboxed(yann,elsa);
  %%drawboxed(david,sarah);
  %%
  drawboxed(yann,elsa,david,sarah);
endfig;
end