actually they stack but do not stack well compared to TG.
from ro data zone
http://rodatazone.simgaming.net/mechanics/attacks.php
21. Apply Damage Bonus modifiers.
Damage Bonuses are based on Size, Family, Elemental Property and Special. Bonuses of the same type stack, while bonuses of differing types multiply together. The overall calculation can be expressed as (1+SizeBonusesTotal/100) * (1+FamilyBonusesTotal/100) * (1+PropertyBonusesTotal/100) * (1+SpecialBonusesTotal/100).
Many cards and other equipment can give Size, Family or Elemental Property Bonuses.
Currently, there are no known Special Bonuses.
FBH&Goldenring=FamilyBonus, SkelWorker=SizeBonus, TG falls in another category creating it own parenthesis
(1+SizeBonusesTotal/100) * (1+FamilyBonusesTotal/100) * (1+PropertyBonusesTotal/100)
e.g. 2FBH, 2TG 1SkelWorker
((1+.15(1[skelWorker])) * (1+.5*(2[FBH])) * (1) * (1+.2(2[TG])) = 3.22 Damage Modifier
e.g. 2FBH, 2TG, 1Goldenring
(1) * (1+.5*(2[FBH])+.25(1[Goldenring])) * (1) * (1+.2(2[TG])) = 3.15 Damage Modifier
e.g. 2FBH, 1TG, 2Goldenring
(1) * (1+.5*(2[FBH])+.25(2[Goldenring])) * (1) * (1+.2(1[TG])) = 3 Damage Modifier
The idea is to have the right amount of varying cards giving bonus to size, family and property and other damage modifiers.
Sorry for the geeky post.
i misclicked the vote this post down XD sorry [GM] Justice