Eustache 1er de Fiennes, seigneur et baron de Fiennes, croisade - I see no proof that Eustach I de Fiennes is a son of Lambert I de Louvain

Note also that Cawley in his bio on Mathilde daughter of Lambert I says that Eustache is son of BAUDOUIN Comte [de Boulogne] & his wife Adelais of Holland (-[1049]).

But then in the section on the comte de Boulogne he seems hesitant to make a three generation connection. I think that at this point Eustache should be disconnected from Lambert and reconnected to Baudouin. Whether or not to connect Baudoin upward as shown to be “possible” is still open to discussion.

The son of Baudouin de Boulogne must be the missing Eustache, possibly.

But we're not finished yet:

https://www.geni.com/family-tree/index/6000000002215326285

The son of Baudouin de Boulogne seems to have been older than the alleged son of Lambert.

For the moment, I'm inclining to the hypothesis that the Baudouin line is correct until somewhat 1050, but that there must have been 1 extra Eustache (IV?) who participated in the first crusade and that we end up with a double numbering beginning from Eustache (V/II) in the early 12th century.

I'd say David, try if you can update the tree in that manner, I' ll join you if we agree.

KR, CGV

https://www.genealogieonline.nl/stamboom-van-den-eijnde/I57045483.php

Genealogieonline.nl gives also Lambert as father of Eustache...

Alle the Eustaches: Brabant line and boulogne line:
(Eustache I c.1010 son of Lambert?
https://www.stamboomzoeker.nl/search?s=25&fn=&sn=de+fiennes...

Eustache the crusader (c.1070) from the Boulogne line
https://www.genealogieonline.nl/stamboom-bert-truijens/I59529.php

Hi David,

I’ve detached Eustache the crusader from Lambert of Leuven, the new data are mainly from genealogieonline.nl and the new situation seems credible, although some finishing touches is still needed. As we know, there was an in-law relationship with the duchy of Brabant.

Thanks for the discovery!
KR, CGV

I’ll dig deep...

Believe it or not but this is the result of tracking back and tracking parallel to de Fiennes and de Bois and a line of de Fienes that have more English names and titles like

Keeper of the Coast
Alan de Fienes 1154–89
James de Fienes 1189–99

Lord Wardens of the Cinque Ports & Constables of Dover Castle
John de Fiennes 1084-1085
James de Fiennes 1085-1111
John de Fiennes 1111-1138 the younger, son of James

Which side of the coast though but it sounds (heraldry source shows the French side wardens using the English coat of arms) more like they could be part of the line that held Dover castle but the dates are curiously parallel to the French side who were wardens of the Cinque Ports. I wonder if there was a cross-channel monopoly, but I have to check these dates against the English activities in Normandy, the English king could have established the English family as wardens but the name similarities would suggest descendency from the same family.

I'm fairly convinced that after 1066 (Hastings) it was one powerful family at both siders of the English channel..