My daughter self-weaned at about 2.5 years old.
It was my choice for self-weaning with both my kids.
However, my boob are my boobs. I taught my daughter that.
I taught my daughter 'manners' about it. Never grab me and to ask nicely.
Not in public.
If she asked, I would sometimes tell her 'Mommy is busy, in a minute..." then I would make myself 'busy' and NOT sit down or lay down. And she would then get distracted and forget about it.
A child will naturally, decrease in frequency.
Then one day, my daughter told ME "I don't drink from you anymore...." and then she giggled like she thought is was so ridiculous that she was nursing. And that was the end of it. Never again, did she 'nurse.'
My son, self-weaned at about 1 year old.
He would literally SLAP my boobs away, and HATE nursing by then, and was just done. He'd say "NO."
I would also talk with my daughter, and explain that one-day, she will not need to nurse.
Of course by this age, my daughter was eating regular foods and drinking whole milk.
She NEVER took a bottle either.
Your daughter at this age, does not 'need' only breastmilk. Going away for 2 days, is not harmful to her, nutritionally.
I am sure he has a 'lovey' and other things to comfort with?
I am sure he will be fine!
all the best,
Susan