Three west suburban law firms on Monday announced they will be merging their practices into one firm effective Friday.

The new firm will be known as Momkus, McCluskey, Roberts LLC, and will consist of attorneys from Momkus, McCluskey LLC, Nyberg & Cassioppi LLC and Roberts P.C.

The attorneys who will be a part of the new firm described the merger as “complementary” in that each practice brings something new to the table.

Edward J. Momkus said his firm has a commercial litigation practice but lacks the expertise and manpower to expand into divorce law and estate planning — areas that Roberts and Nyberg & Cassioppi each focus on.

“We get a lot of synergy in putting this set of lawyers together because the skill sets are so complimentary,” said Momkus, a founding member of the firm. “It’s very much a strategic merger — and everyone benefits.”

Wheaton-based Roberts and Naperville-based Nyberg & Cassioppi each currently have five attorneys on staff.

Momkus, McCluskey, based in Lisle, has 24 attorneys. After the merger, the new firm will have 31 attorneys in the Lisle office, according to a joint news release from the three firms.

Gerald A. Cassioppi, a partner at Nyberg & Cassioppi, said he wants his firm to be a “one-stop shop” for his clients, but this can be difficult for a smaller firm.

“If we can continue to provide this fulsome approach to legal services, then you don’t have to be referring out from a business perspective and capture virtually any legal service anyone wants,” Cassioppi said.

Cassioppi added that the merger would allow the different law firms to expand rapidly as opposed to “one or two lawyers at a time.”

“It really gets us to where we want to be in this market a lot quicker,” he said.

Keith E. Roberts Jr., a shareholder at Roberts, said in the release: “The merger provides our clients with even broader litigation resources and allows us to expand our presence in and beyond DuPage County.”

Momkus touted the new firm as being one of the largest in DuPage County, and he’s hoping for it to get bigger. He said he wants to continue to expand the firm so it has 50 attorneys.

Three attorneys are not making the jump to the new firm — William D. Cherny of Nyberg & Cassioppi, Robert S. Marcott and Robert W. Funk II of Roberts.

When asked why he wasn’t joining the new firm, Cherny said he has his own practice; as an of counsel, he had a transactional relationship with the firm.

“It has worked well but with the merger there are attorneys at Momkus, McCluskey that do what I do and for me to make the move may be a duplication of effort,” Cherny said.

Cherny praised the merger as being a boon to the firms as well as their clients.

Roberts, Marcott and Funk did not return requests for comment.

Momkus said the three firms had previously discussed the possibility of merging together before, but serious talks about it did not begin until late last year.

Momkus described the merger as being part of a plan in order to select successors for himself and James F. McCluskey, another founding firm member.

Momkus said he plans to retire from the full-time practice of law in the next two to three years.

Meanwhile, McCluskey is set to become the president of the Illinois State Bar Association in 2018. Momkus indicated someone will have to cover for McCluskey once his ISBA duties take priority.

“This is one of these things where the proverbial [firm] started in my basement, and I wouldn’t mind looking up 10 years from now to see it prospering,” Momkus said. “We want to solidify its future.”