associate text with chords

[achar]

Hello.
Here is a piece of code to explain my problem. 
I would like the roman numerals of the mib7 chord as well as that of do7 
to be located under the chord names. But the text is associated with a note or a rest 
so I can't do it. Does anyone have a solution? Thank you.
P.S.: I already received answers but, they evaporated before I could read them

<<
  \chords { bes2:m7 ees:7
  s1
  g2:m7 c:7
  }
  \new Staff \relative c''
  {
     f4_"ii / V" aes2 g4_"V7 /IV"   
     R1
     \break
      bes1_"iii m7 - V7 / ii" |
      
      R1
     \break
     
  }
>>