Any benefit to retaining smaller cornish cross from lot?

[goats-n-oats]

Hi, there are 20 straight run Cornish crosses from TSC here. One of them turned out to be a silkie (not pictured here), and one looks like a heritage pullet. Her legs and feet are thick like the cornishes but her small body size and shape look more like a heritage bird. Do you think this is a Cornish? Would there be any benefit to retaining her to breed with my backyard flock of heritage birds?

The bird at the top of this photo

 

[Molpet]

I kept a CX pullet in 2016 and most of my flock are out of her cockerels. Her pullet laid double yolk eggs. She quit laying for the winter and died before she was a year. Diet and exercise is important to keep them alive long enough to lay.
Lots of CX people have kept for breeding end up laying double yolk.
I harvest the cockerels around 16 wks and they dress out around 5 to 7 lbs.

 

[goats-n-oats]

How did you tell the gender of the store bought hen at eight weeks?

I kept a CX pullet in 2016 and most of my flock are out of her cockerels. Her pullet laid double yolk eggs. She quit laying for the winter and died before she was a year. Diet and exercise is important to keep them alive long enough to lay.
Lots of CX people have kept for breeding end up laying double yolk.
I harvest the cockerels around 16 wks and they dress out around 5 to 7 lbs.

 

[FrostRanger]

How did you tell the gender of the store bought hen at eight weeks?

Males usually have earlier comb and wattle development and will generally have bigger and redder combs and wattles at this age. Some boys will even be crowing. Those are the main early signs

 

[Molpet]

How did you tell the gender of the store bought hen at eight weeks?

I bought 2 barred Rock and 6 CX. All were sold as pullets. One br was a cockerel and all the CX were pullets. At 2 weeks I read about a guy using CX for breeding by feeding 2x a day for 20 minutes. So I started right then . I kept the one that roamed the most.

 

[goats-n-oats]

So

I bought 2 barred Rock and 6 CX. All were sold as pullets. One br was a cockerel and all the CX were pullets. At 2 weeks I read about a guy using CX for breeding by feeding 2x a day for 20 minutes. So I started right then . I kept the one that roamed the most.

So you're saying you kept the most agile female and bred her with heritage roosters and the result was faster growing heritage meat birds?

 

[Molpet]

So

So you're saying you kept the most agile female and bred her with heritage roosters and the result was faster growing heritage meat birds?

Yes
This was my inspiration
https://www.backyardchickens.com/threads/toad-raising.1152440/