Dear Katherine, 

Thanks for this good question, Early offer donor milk affects maternal milk contribution check these links for your answer http://journals.sagepub.com/doi/pdf/10.1177/0890334416632203

Journal of Perinatology 33, 446-451 (June 2013) | doi:10.1038/jp.2012.153

Here is some work from our group addressing this question:

https://www.researchgate.net/publication/261761691_The_Effect_of_a_Donor_Milk_Policy_on_the_Diet_of_Very_Low_Birth_Weight_Infants

Article The Effect of a Donor Milk Policy on the Diet of Very Low Bi...

This is an interesting topic.

Lactation is affected by the maternal mood, for sure.  Seeing her infant receive donor milk may have very different emotional consequences. Therefore, a mother may feel less stressed to see her infant getting fed, and less stress may increase her milk letdown. on the other hand, she might get distressed to see her infant to be fed by donor milk, get jealous or may get feelings of inadequacy, and her milk let down decrease. 

This is an interesting question, I am looking forward to see your results in the long time. 

Most studies show that access to banked milk actually increases lactation rates for NICU moms. Some relevant papers: