BOSTON — Growing up in Bath, Maine, Bruce Gillies Sr. never dreamt of building a dynasty.

Sitting in Section 15 at the TD Garden on Thursday, immersed in an extended family clad in black, white and silver, he pointed to his grandson, Jon, standing guard in the Providence College crease, and to the defensemen flailing through the defensive zone helping block a barrage of shots.

“They didn’t do that for me,” Bruce said, a wry smile creeping across his face.

Indeed, when the elder Gillies left Bath to play for Norwich University in Vermont, defensemen weren’t in the habit of sliding to block shots.

Case in point: Bruce stood tall in the cage for Norwich when they faced off against the Bates Fabrics in Lewiston on Sunday, Dec. 26, 1954 at St. Dominic Arena. He made 50 saves that night against the likes of local legends Dick Lafrance, Roland Chalifoux and Ray Dube. He also allowed nine goals in a 9-5 loss.

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Sixty-one years later, still tall and slender, and still very much a goalie at heart, Gillies Sr. gazes intently at the ice. Beside him, an empty seat belonging to his son, Bruce Jr., and then a trio of players’ mothers, including his daughter-in-law, Debbie.

“He can’t sit there,” Debbie says of Bruce Jr., gesturing back and forth. “He paces.”

Bruce Jr. was much more calm and confident when he played for the University of New Hampshire in the early 1980s. Like his father, he played between the pipes, and helped the Wildcats make the transition to Hockey East in the conference’s infancy. Bruce Jr.’s brother, Chris, also played Division I hockey as — you guessed it — a goalie, for the University of Denver from 1985-89.

Jon, the third generation of Gillies men to skate for an NCAA varsity team, slides quickly to make a save after a teammate nearly kicked it into his own cage.

Debbie does not pace. She cringes. She clutches friend and fellow mother Heather Adams. She hoots and hollers.

If a voice could stop a puck, she would be a first-team All-American.

“It’s so nerve-wracking,” Debbie says. “And it’s so much worse when it’s tied.”

At the start of the second period, Thursday’s first of two NCAA Frozen Four semifinals between the Friars and University of Nebraska-Omaha Mavericks is knotted at zero. Debbie’s feet tip and tap and tip and tap as the puck slides into the Providence zone.

“It’s a little different here,” she says. “In Providence, we’re right on top of them when they play.”

That doesn’t stop Debbie, Heather Adams and Edna Acciari from making noise. And plenty of it.

“We’re all BFF’s,” Debbie says. “We have our little cheering section.”

As if on cue, Edna’s son, Noel, scores at 11:02 of the second period, sending Section 15 into a frenzy.

Bruce Sr., stoic in expression as he analyzes the game, stands in approval, again flashing his grin. He watches his grandson’s reaction.

Is it easier tied, or easier with a lead?

“With a lead, for sure,” He says.

Debbie’s not so sure.

“It’s hard with a small lead, more nervous for us.”

She hardly finishes speaking when Mark Jankowski doubles the Providence lead.

Again, the section erupts. High-fives all around.

“We still need another one, though, maybe two more,” Debbie says. You saw what happened against Miami.”

In the third period of the teams’ first-round NCAA matchup, Providence held a 6-2 lead before the Redhawks rallied for three goals with the goalie pulled, creating tense moments among the Friars faithful.

“Someone asked me, ‘Why are they pulling the goalie with almost three minutes left?’” Debbie recalls. “I said, ‘That’s a great coaching move, they need goals.’”

She’s seen her share of hockey games, and her share of coaching decisions, over the years.

Confirming Debbie’s fears, Jake Guentzel cuts the Providence lead in half at 10:46 of the third period. The pressure is back on Jon. And Debbie. And Bruce Jr. And Bruce Sr.

Trevor Mingola puts Providence back on top 24 seconds later. Relief.

“We still want more, though,” Debbie says.

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After an empty-net goal in the final minute and behind Jon’s 25 saves, the Gillies clan and the Providence faithful will get more — one more game, win or lose.

Jon has already accomplished more as a keeper than his familial predecessors. He’s been drafted to the National Hockey League. He’s skated for his country in the World Junior Championships.

Saturday, he could become a national champion.

Debbie, Heather Adams and Edna Acciari will be there. Bruce Jr. will be there — somewhere.

And Bruce Sr. will most certainly be there. Stoic, pensive, thoughtful, he’ll admire his favorite active goaltender — his grandson — the latest in a family dynasty he unwittingly founded so many years ago.