On 22 Jun 1700 when Robert was 22, he married Susanna Briggs (18802) , daughter of William Briggs (6772) (1650-12 May 1716) & Elizabeth Cook (6966) (1653-Aug 1716), in Little Compton, RI.374,271 They were married by Joseph Church, Justice. Born on 9 Apr 1681 in Little Compton, RI.271 Susanna died in Tiverton, RI, on 2 Apr 1744; she was 62.

Children of Robert and Susanna (Briggs) Dennis, first three born at Little Compton, others at Tiverton:374
    i. Comfort Dennis, b. 12 Mar 1703;
    ii. Anna Dennis, b. 3 Jul 1704;
    iii. John Dennis, b. 24 Jun 1706;
    iv. Humphrey Dennis, b. 12 May 1708, d. 23 Dec 1729 at Tiverton;
    v. Thomas Dennis, b. 17 Mar 1710;
    vi. Tabitha Dennis, b. 8 Sep 1712;
    vii. Elizabeth Dennis, b. 23 Sep 1714, d. youn;
    viii. Sarah Dennis, b. 2 Nov 1716, m. 1 May 1733 Cornelius Soule;
    ix. Lydia Dennis, twin, b. 18 Feb 1718, m. 10 Mar 1743/4 Simeon Palmer (b. 13 Jul 1723 at Little Compton, son of John and Sarah (Blood) Palmer);
    x. Elizabeth Dennis, twin, b. 18 Feb 1718;
    xi. Deborah Dennis, b. 21 Mar 1721/2, m. 6 Jan 1745/6 Paul Brownell; and
    xii. Mary Dennis, b. 3 Nov 1723, m. 12 Oct 1746 Joseph Crandall.

Ca 1704 John married Ann Brayton (22858) , daughter of Stephen Brayton (ca 1654-ca 1692) & Ann Tallman (8587) (ca 1656-ca 1732). Born on 6 Jul 1683 in Portsmouth, RI.322 Ann died in Newport, RI, on 28 Aug 1747; she was 64.

On 20 Apr 1721 when Joseph was 31, he married Sarah Durfee (35526) , daughter of Thomas Durfee (17009) (28 Mar 1669-11 Feb 1729) & Anna Freeborn (28 Mar 1669-ca 1729), in Portsmouth, RI.322 They were married by William Sanford, Justice. Born 1 Mar 1692/3 in Portsmouth, RI. Sarah died in Portsmouth, RI on 21 Apr 1759.322

Children of Joseph and Sarah (Durfee) Dennis, born at Portsmouth:322
    i. Sarah Dennis, b. 1 Jul 1723, d. 25 Aug 1723;
    ii. Sarah Dennis, b. 1 Apr 1725, d. 26 Jan 1728;
    iii. Robert Dennis, b. 12 Sep 1727, d. 12 Apr 1811 at Portsmouth, m. there 1 Jun 1750 Hannah Coggeshall (b. 3 may 1731 at Middletown, RI, d. 22 Nov 1811 at Newport, dau. of Thomas & Mercy (Freeborn) Coggeshall);
    iv. Joseph Dennis, b. 15 Jan 1729, d. 28 Sep 1758;
    v. Ann Dennis, b. 19 Dec 1731;
    vi. Ruth Dennis, b. 6 Dec 1733;
    vii. Lydia Dennis, b. 12 Oct 1735, d. 13 Mar 1779 at Portsmouth, m. there 16 Dec 1757 David Fish (b. 15 Mar 1733/4 at Portsmouth, d. before 1779, son of David & Jemima (Tallman) Fish); and
    viii. Freeborn Dennis, b. 18 Aug 1739.