One of our clients looking to redesign their website since we're redesigning the whole website we thought it would be good idea to separate services into individual pages so every service will have it's own page (currently there is 1 page that describes all of the services). what we're planing to do is to write unique content for each service page (about 300-400 keywords), but we also want to use some of the existing content which is kind of explains the process of provided services.

so here i need your help!

what would be the best practice to use same part of existing content on every service page without getting penalized for duplicated content?

here is how we want to structure the page with h1 and h2

<main>

Service name (same as page title)

Subline

new and unique content about 300-400 keywords

Part of old content which is going to be placed on every service page

</main>

any help would be much appreciated!