How do you use OLYE (instead) here? "I'll have water instead"

You should use PITO here.
olye - in place of, rather than, instead of
pito adv - instead, preferably, rather

FYI: pito v → to prefer; it is preferable that, it is better to

1. I'll have water instead.
    M'ap pran dlo pito.
    but you can say:
    I'll have water instead of coffee.
    Olye kafe, m'ap pran dlo.

2. Let's go to the movies instead.
    Ann al nan sinema pito.
    or you can say:
    Olye pou n al nan konsè a, pa pito n t'al nan sinema.
    Instead of the concert, what if we go to the movies?

3. I prefer to have a salad instead.
    Mwen pito pran yon salad.

4.  Olye pou ap gaspiye tan w la a, pa pito ou te tounen lekòl.
      Instead of wasting your time here, wouldn't it be better if you went back to school?

5. Olye pou ap babye pou frijidè a ki vid, pa pito w ta al fè makèt.
     Instead of nagging about the empty fridge, why don't you go to the market?

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