Conservative MPs Fiona Bruce (pictured right) and Caroline Spelman (pictured left) are among the signatories of a new family charter which makes 18 recommendations.
Fiona Bruce said: "These family policies have commanded a very strong show of support from MPs.
"As the Prime Minister returns to Downing Street after the summer recess this manifesto ensures that she will be well-equipped to make tackling family breakdown a top priority."
The charter - backed by 44 Conservatives - urges the Government to tackle aspects of the tax and benefit systems which they say encourage mothers and fathers to live apart.
It also calls for a Cabinet minister dedicated for families and for a minister in every Whitehall department to be tasked with ensuring policies are family-friendly.
Fiona Bruce added: "If we want to address some of the biggest issues facing people up and down the country, such as soaring levels of childhood mental illness, stubbornly low rates of upwards social mobility, addictions, housing shortages and loneliness in older age, looking at how to strengthen family relationships is the place to start.
"This manifesto will help the Prime Minister to achieve her aim to make Britain a fairer country, one that works for everyone, not just the privileged few."
Other signatories to the manifesto include former Work and Pensions Secretary Iain Duncan Smith and former Education Secretary Nicky Morgan.