I would say - Just do it. When our son married, there were the usual speeches. Like you, my husband wanted to say something about our son. As the Father of the Bride was 'winging it', and the guests were fidgeting, and I was sitting next to the Best Man on the evening, I suggested to him that the Father of the Groom would like to say a few words too. My husband stood up and did just that: lots of smiles all round, lots of clapping, and with the guests now all 'warmed up' we moved quickly on to the Best Man's very humorous speech. BTW, the Father of the Bride thanked us as he said was nervous about his speech.