How to restrain to some specified waters for OPC model

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GROMACS version:2021.6
GROMACS modification: No
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Dear Gromacs users
I have the same problem as in
How to treat specific water molecules as ligand?.

I’m setting .top file for MD simulation with OPC model for water.
I want to use positional constraints on the three waters(name: FIX) that coordinate to the sodium ion.
Using the above link’s answer, I have rewritten the [settles] section.

Are there any other sections to be rewritten?

[ moleculetype ]
; Name            nrexcl
FIX          3

[ atoms ]
;   nr       type  resnr residue  atom   cgnr    charge       mass  typeB    chargeB      massB
; residue    1 FIX rtp FIX q 0.0
    1         OW      1    FIX      O      1 0.00000000  16.000000   ; qtot 0.000000
    2         HW      1    FIX     H1      2 0.67914200   1.008000   ; qtot 0.679142
    3         HW      1    FIX     H2      3 0.67914200   1.008000   ; qtot 1.358284
    4         EP      1    FIX    EPW      4 -1.35828400   0.000000   ; qtot 0.000000

#ifdef FLEXIBLE

[ bonds ]
;    ai     aj funct         c0         c1         c2         c3
      2      1     1   0.08724 462750.400000
      3      2     1   0.13712 462750.400000
      3      1     1   0.08724 462750.400000


#else

[ constraints ]
1 2 1 0.08724331
1 3 1 0.08724331
2 3 1 0.13712051


#endif

[ virtual_sites3 ]
; Site  from                   funct
4     1    2    3    1      0.147721  0.147721

[ exclusions ]
1  2  3  4
2  1  3  4
3  1  2  4
4  1  2  3

#ifdef REST_ON
#include "/home/itp/posre_FIX.itp"
#endif