Table:
0
A
B
C
D
E
F
G
H
1
Name
Father
Birth
Marriage
Became Countess
Ceased to be Countess
Death
Spouse
2
Margaret of Bavaria
Albert I, Duke of Bavaria ( Wittelsbach )
1363
12 April 1385
21 March 1405 husband's accession
10 September 1419 husband's death
23 January 1423
John
3
Michèle de Valois
Charles VI of France ( Valois )
11 January 1395
June 1409
10 September 1419 husband's accession
8 July 1422
8 July 1422
Philip II
4
Bonne of Artois
Philip of Artois, Count of Eu ( Artois )
1396
30 November 1424
30 November 1424
17 September 1425
17 September 1425
Philip II
5
Isabella of Portugal
John I of Portugal ( Aviz )
21 February 1397
7 January 1430
7 January 1430
15 July 1467 husband's death
17 December 1471
Philip II
6
Margaret of York
Richard Plantagenet, 3rd Duke of York ( York )
3 May 1446
9 July 1468
9 July 1468
5 January 1477 husband's death
23 November 1503
Charles II

Questions and formulas:
Question: When did the person born on 3 May 1446 cease to be countess?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:H1,C1="3 may 1446"),6))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:H6,C2:C6="3 may 1446"),6))
Level: medium
Question: Who was the father of the person born in 1363?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:H1,C1="1363"),2))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:H6,C2:C6="1363"),2))
Level: medium
Question: When was the marriage of the person who died on 17 December 1471?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:H1,G1="17 december 1471"),4))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:H6,G2:G6="17 december 1471"),4))
Level: medium