I suppose her husband could just as easily be described as a scion of the Earls of Iveagh, but his line is generally included in the Burke's article on the Baronets. The common male-line ancestor died 250 years ago, so the relationship to either is the same, but quite distant.
As for Bianca:
Caroline Bonaparte, b.Ajaccio 25 Mar 1782, d.Florence 18 May 1839; m.Mortefontaine 20 Jan 1800 Prince Joachim Murat, King of Naples and Sicily (1767-1815)
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Princess Letizia Murat, b.Paris 1802, d.Bologna 1859; m.Venice 1823 Guido Taddeo Marchese Pepoli, Cte di Castiglione (Bologna 1789-Bologna 1852)
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Elisabetta Pepoli (Bologna 1829-Rome 1892); m.Rome 1848 Ippolito Ruspoli (Rome 1817-Rome 1886)
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Letizia Ruspoli (Rome 1849-Rome 1944); m.Rome 1871 Mario Rappini Marchese di Casteldelfino (Rome 1834-Rome 1899)
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Vittorio Rappini (Rome 1877-Rome 1939); m.London 1912 Clara Dudgeon (Shanghai 1885-Fiesole 1954)
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Isabella Letizia Rappini (London 1913-London 1986); m.Varese 1934 Renzo della Pura Onorati (Pisa 1904-Florence 1975)
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Bianca della Pura Onorati (Padua 1941-8 Apr 2022); m.Florence 1966 Hugh Welby de Capell Brooke Guinness (2 Oct 1937-30 Jul 2014)