describe the location of the blueprint that determine the structure of each of these forelimbs as the organism develops from embryo to infant

The DNA in the nucleus.

Explanation:

The blueprint that contains all of the instructions to "build" and maintain an organism is found in the DNA.

The DNA is the hereditary molecule found in the cell nucleus. The sequence of the DNA determines the expression of genes, which make proteins in the cell. Proteins carry out essentially every function in the cell, including dictating the development of forelimbs.

Therefore, all the information required for the organism to develop is encoded in the DNA.