The league is interested in the circumstances surrounding Harden declining his $47million player option to sign a two-year, $68m contract that includes a player option for the second year of the deal.
Questions have been raised about whether there was a handshake agreement in place on a future contract – which would be in violation of collective bargaining rules.
Harden’s decision to decline his option gave Philadelphia more flexibility to sign Tucker and House.
"Taking less money this year to sign as many players as we needed to help us contend and be the last team standing was very, very important to me," Harden said in an interview this month. "I wanted to show the organisation, the Sixers fans and everybody else who supports what we're trying to accomplish, what I'm trying to accomplish individually, that this is what I'm about."
Tucker signed a three-year, $30m contract, and House signed for $8.4m over two years. The 76ers were able to sign Tucker to the full mid-level exception and sign House to the bi-annual exception only because Harden declined his option.
According to the report, 76ers president of basketball operations Daryl Morey has already begun answering questions from league attorneys.
With tampering often a potential issue, the NBA approved stiffer penalties in 2019 and stripped a draft pick from the Chicago Bulls for early contact with Lonzo Ball in 2019, and the Miami Heat for doing the same with Kyle Lowry last summer.
The Rockets (2-16) were down 10 midway through the third quarter and appeared to be heading towards their 16th consecutive loss before a 27-9 run turned the game around.
Silas, whose future came under scrutiny before Wednesday's clash, saw his team storm back to claim a 118-113 triumph, with House starring off the bench.
The 28-year-old managed 18 points in 17 minutes as a replacement, with all those coming in the second half as Houston made eight of their 11 three-point attempts in the decisive third quarter.
After the game, Silas praised the impact of House, who did not feature at all in the first half before the Bulls were outscored 35-18 by Houston in the penultimate quarter.
''He's been in and out of the rotation,'' Silas said. ''He played eight minutes the last game.
"I wanted to get him out there just so he could continue to believe that his work would pay off, and tonight, he was the difference maker really.
"It feels good, and when you make 17 threes it looks a lot better. We were getting some of those shots previously and shooting 25 per cent instead of 47 per cent. We were in our spacing spots. It looked a lot better because we were making them."
Chicago coach Billy Donovan bemoaned his side's lack of aggressiveness after half-time at United Center, with Zach LaVine's 28-point return in vain.
"We just came out and kind of messed around with the game, and before you know it, we're down by 10 after being up by 10,'' Donovan said.
''I have to help this group solve it and figure that part of it out. We're a very good team, but we are not so good that we cannot show up and play in a quarter in an NBA game and expect to win."
