Fix the page first, then point the links at it.
A link tells Google a page matters; if the page does not answer the search, the link has nothing to lift. A firm with a website for each office merges them into one first, so every link builds the same site, and links follow every month from the second or third. Your attorney SEO company should price links with the rest of the work, after reading the site, because the pages that are ready decide how many links are worth building.
Earn them where the firm is already known.
The links worth having name the firm for something real: a lawyer's profile on a bar association site, a quote in the local paper, a talk at a law school, a local organization the firm supports, a guide another site cites. Each points at the page for the practice it is about, in words that describe that page. Guides worth citing are the work of law firm content marketing.
A paid link is advertising, under Google's rules and your bar's.
Google asks for paid placements to be marked sponsored. The bar's rules govern anything that recommends a lawyer or trades referrals: ABA Model Rule 7.2 allows a reciprocal referral arrangement only if it is not exclusive and clients are told about it, and it limits who may be called a certified specialist. The firm's counsel decides those questions, and the link plan follows the answer.