The phrase "afterwards adding" is correct and usable in written English.
It can be used to indicate that something is being added after a previous action or event has taken place.
Example: "She completed the report, afterwards adding her final thoughts in the conclusion section."
Alternatives: "subsequently adding" or "then adding".
"They have some wheels and a half," said Spithill afterwards, adding: "Ben did a great job".
What doesn't kill us makes us stronger," Ancelotti smiled afterwards, adding: "I'm joking: I'm not a philosopher.
"I was really happy when Karpin got sent off," he sniped afterwards, adding: "he's really arrogant and a real chulo".
"He's very good with the ball at his feet," said Villas-Boas's assistant, Steffen Freund, afterwards, adding: "It's nice to see the young players doing so well".
"I didn't think I deserved it," Vieira said afterwards, adding graciously: "But I make mistakes so I have to accept it when the referee does".
"He's very good with the ball at his feet," said Villas-Boas's assistant, Steffen Freund, afterwards, adding: "It's nice to see the young players doing so well". One of the older ones also took his opportunity.
Furthermore, we tested the barrier function by treating HMVEC-L with LPS for 6 hours and afterwards added an EP4 receptor-agonist, ONO AE1 329 (30 nM).
"I spoke to him in the dressing-room afterwards," added McCall.
"I started off doing the ground game and jiu-jitsu, and then moved on to striking afterwards," adds Sass.
It had been developed for an appearance on Heston's Feasts, and was afterwards added to the menu at the restaurant.
At the time of transfection cells in each well were first washed in 2 ml Dulbecco's Phosphate Buffered Saline (PBS) brought to room temperature and afterwards added 1.2 ml of a 6.3 µg/ml Lipofectamine 2000 in OptiMEM I solution.
