The phrase "and more particularly when" is correct and usable in written English.
It can be used to specify a particular situation or condition that is being discussed in more detail.
Example: "The project is challenging, and more particularly when deadlines are tight."
Alternatives: "especially when" or "specifically when".
Investigators said Daniel's mother, a single parent who worked at Wal-Mart and the school, should have done more, particularly when he had been late or absent 74 out of 78 school days.
It is important to define an acceptable trade-off between the number of available satellite tracks and the level of external field activity, more particularly when processing the data on regional scales because the local functions require a dense data coverage in space.
The film has already won him the screenplay prize at Venice (he co-wrote with Grant Heslov) and I can see it going on to scoop several more, particularly when the Academy voter puts pen to paper.
But shopping will cost more, particularly when it comes to clothing.
More particularly, when I first saw the Tony-winning Off Broadway musical "Once," it struck me as too twee, though I loved its music and its dance.
Because in movies like "Friday the 13th" less is never more, particularly when it comes to showcasing comely teenagers (a k a the victims).
But the Pentagon, which spends $50 billion a year on health care, said that it was fair to charge the best-paid retirees more, particularly when many pursue second careers after leaving the military.
Millennials are craving something more, particularly when it comes to flexibility in a work environment.
The Kraft campaigns are indicative of how ads from mainstream marketers are loosening up — or becoming crass and crude, depending on your perspective — to reflect changing societal mores, particularly when it comes to younger shoppers.
But it is the story of Mr. Guerrero's life, told in his own modest words, that is richer and more urgent, particularly when he writes about serving as the sole dove on a draft board during the Vietnam War, which cost him a lucrative 20-year career at House & Garden.
