How could they not love them? They are made with love.
Sadly, however much love with which they are made, they could be a gift of death. The Fire Services in the UK, NewZealand and Australia are seriously concerned about the fire and smoke inhalation dangers posed by wheat and other grain heat packs. In addition, there have been numerous papers and reports of them causing serious skin burns. Just google some appropriate terms.
The dangers of them under other incorrect usage are not well-known at all.
There is a (voluntary)British Standard for such heat packs, which centres mostly on permanently-attached clear and comprehensive instructions on their safe use.
PLEASE ensure that any you might give as gifts are accompanied by clear and comprehensive instructions for their safe use.
I have dissected dolls, and that is how the type of baby doll which has a soft body, but 'formed' legs, arms and head, are made. The 'brand' name ones, such as BabyBorn and Baby Annabell have this tie pretty well disguised - the fabric portion of the limbis usually attached to the formed portion while it (the fabric portion) is inside out, so when it's turned the right way round for stuffing, the method of attachment is totally concealed. Around the head/neck, there is a casing of the body fabric through which the tie runs, at the point where it has been pulled tight and cut off, there are usually a few firm hand stitches which ensure even the 'buckle' bit of the tie remains concealed by a casing of fabric.
However, if you look at a cheap 'generic' soft-bodied doll, although the attachment of the limbs is usually concealed, the fastened bit of the cable tie is often very clear around the neck. It is - usually - on the side of the neck on the doll's right.
Buy a cheap soft-bodied baby doll from a discount shop or a brand name one - or several - from a charity/thrift/op shop, strip it naked and cut it apart, carefully, to see how it is constructed. Brand name ones and generic ones are constructed very differently, I have found. It's no use my posting pix, as the cable tie is white, against white or pale pink fabric, or tan or dark brown against tan or dark brown fabric.
If, at the bottom of the head/base of the neck/hand/foot/wrist/wherever, there is a groove in the polymer clay which goes all the way round the circumference of said 'joint', and just distal to that groove is a ridge, the fabric for the limb/body/wherever can be securely attached by means of a cable tie of suitable length, colour and width. Excess is trimmed off, and excess fabric turned over to conceal the tie, and also trimmed as necessary, or fur brushed so as to disguise the tie, or mohair added with glue, or clothes fitted - whatever. You could even use glue in the groove as well as the cable tie if you didn't trust yourself to get it tight enough.
This is a very useful technique for securely and discreetly attaching solid or semi-solid extremities to a soft fabric body.
Quite a few Scandinavian magazines include sewing patterns for Build-a-Bear clothing. I have patterns for a Father Christmas suit, a rainsuit, PJs, a Santa Lucia gown, a hoodie and trousers from various Danish magazines. Some of them are available as downloads from http://www.hendesverden.dk
Velcro will be fine; I make lots of dolls clothes and use velcro constantly. Depending on the position of the fastening, and how I want it to look, sometimes I will sew one bit of the velcro onto a small tab; on some fabrics (check yours) you don't need to use any loop fabric as the whole garment acts as the loop - these fabrics are ones to use with elastic or any other fastening than velcro, IMO!