this way, is way, all the donations you collect go straight to the people you are working to help ― making your donors feel certain (that)their dollars are doing good things

빨간 부분에 that이 생략될수가 있나요?
feel that 은 이해가 가는데
feel + 형용사 다음도 that 이 올 수 있는지 답변부탁드립니다..