The first step in the massive undertaking of replacing the massive Dexter Lawrence came last weekend in the sixth round of the NFL draft and the next steps came Wednesday when the Giants signed two veteran defensive tackles to one-year deals. The more notable addition is Shelby Harris , a 34-year-old with 89 career NFL starts. The Giants also signed Leki Fotu, a well-traveled player who has been with four teams in six years. No single player can replicate what Lawrence brought to the defense, so the plan is to attack the problem with multiple players. The Giants could sign another veteran soon. In the draft, they selected Auburn’s Bobby Jamison-Travis in the sixth round. He is a 328-pound run stuffer. Harris is not nearly that big — 6-foot-2, 288 pounds — but arrives as a durable player with a track record of subduing opposing rushing attacks. He has played 146 NFL games (89 starts) with only 28.5 career sacks.…