Outcomes for Runts

I'm rather new at keeping ducks, and I'm wondering what to expect with a runt duckling.

I mail-ordered a box of ducks including 6 Welsh Harlequins. One of the females is 4 weeks old and only half the size of the other females. My plan is to keep two females for the eggs, and a drake, but sell the others. I can't imagine anyone would buy a runt on purpose; so it looks like I'm keeping her for a while, at least.

She has no special needs. She's a little clueless, not noticing that the flock has moved away, then she scrambles to keep up. She gets stepped on, just tries to move out of the way. Some of her face down has been pecked away, making her face look a bit weird. She eats, swims, and walks without any issues. I see some feathers coming in.

What kind of outcomes should I expect for her? Do runts ever catch up in growth or become decent layers or worthwhile mothers? I doubt this breed is a useful meat bird. I want to avoid getting attached to her as a pet. I would not want to breed her.

What to do?

She should catch up to the others she probibly came out of a really small egg

See my avatar? That's Elfie. She was at least two weeks behind the others till she was nearly a year old.

Sounds very similar to yours. I made sure she had some extra vitamins (once I was so concerned I made a batch of vitamin water and held her and made sure she drank some). And I talked to her and cuddled her a little - my Runners have never liked being picked up, but could sometimes be petted.

Anyway, Elf is one heckuva duck! She caught up, she is full of personality, vim and vigor, bright as any of them. Even did a little sumo wrestling with a new duck - I was shocked!

ohh runts can grow and live greta lives they might always be a bit smaller than some other ducks but usually they can catch up

Well, three out of three people expecting hopeful outcomes is helpful! I guess she will stay with me for sure, for her first year.

She definitely won't look at pretty as Elfie (love that name, BTW!). Maybe I'll call her Lemon, because she isn't performing as advertized. I can change it to Lemon-Ada if she turns out well....

I'll work on getting her a nutrient boost, too. That's a good idea.

Let me see if I can find a pic on my phone for you.
Most runts I've raised don't make it past a month. But I have one that's an ancona. He's just over 2 months old now and literally looks like hes still 4 weeks old. His siblings are almost fully feathered and are HUGE. He is small, still fluffy and doesn't have a single feather yet!
But acts healthy and fits in the flock with the rest of them. He was upset when I separated them (out of fear he would get squashed) but now he's back with them as that where he's happiest.

Not the best picture but here he is. The big ducks in the pic are his siblings. The smaller ones (still bigger than him) are 3-4 weeks younger than him!