I've been looking into xsi and have found out that despite some really neat features, there are some topics that are pretty mushed up all together, like parenting... Parenting and constraining are two different concepts universally, regardless of a certain package... But in the case of XSI, that seems not to be the case... In almost all 3D software packages, parented objects inherit the parent's world transformation relative to the pivotal center of the parent. In XSI however, these concepts are all mixed into each other, making it really hard for new the learner to get a grasp how they all work. For instance it just should be really easy to parent the root of a leg bone to the root of a hip bone. In maya, all you have to do is select the child joint and the parent joint and hit p... In XSI though parenting only adds the leg root bone to the hierarchy but the child does not inherit the transformation of the skeletons root. This seems to go for all objects. You have to go ahead and do multiple constrains on it. And from the tutorials I have come across on the internet I have seen that it takes the author to parent the leg bone to the spine root in 4 steps... And he uses a terminology named "relaxing constraints", which I couldn't find in the help files and couldn't understand what it means... I really like XSI, but also believe that it just has a loong way to go before it can catch up with the practicality of Maya...
Hi jacobo,
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In XSI though parenting only adds the leg root bone to the hierarchy but the child does not inherit the transformation of the skeletons root. This seems to go for all objects. You have to go ahead and do multiple constrains on it.
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There is probably a setting that is checked that you don't want: Auto-child compensate. It's in the Constrain menu of the MCP. Uncheck it, and then whenever you SRT the parent, the children should follow without the need of constraints.
When Auto-child compensate is on, the children will compensate their own SRT to stay like they are whatever the parent does.
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And he uses a terminology named "relaxing constraints
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Although I'd be curious to see that tutorial, my guess is that the author is referring to soft contraints. When you apply a constraint, in the ppg you have the choice of using it Rigid or Soft.
Hope this helps
Salutations - Cheers
Bernard Lebel
BTW: No intentions at all to be haughty or patronizing, but I'm not sure that such long introductions (with comparisons with other softwares) is necessary to give depth to your problem 
Just giving the facts is generally enough you know. Take care.
Dear Bernard;
Firstly allow me to thank you for your sincere hospitality in this forum and your help on top of everything. You have been so much help and I appreciate it deeply.
And as for my petty frustration about the Maya vs XSI workflow, I must apologize for it. Unfortunately, the help file of XSI is not designed to orient new users to learn about the ins and outs of the application and I get frustrated when I get lost in it.
I must thank you for your patience and kind support though...
take care;
Aj
Hi Jacobo,
I've always interpreted the term 'relaxing constraints' as 'removing the constraint' after you have applied it. i.e. Constraint > Remove constraint. It's the same as the function ' match all transforms ' in that an object (called A) is set to match another objects (called 
transformation, without beint contrained/parented/in any way linked. This allows you to then reverse the prodedure, so that you can parent object B to object A, without the centre being offset, and so that transformations on the object B will now be 'zeroed' (i.e.Rotation, Translation are all 0, good for the F-curves when u animate!).
Hope this makes sense..
Mr Bo