What to dress a nearly 5 month old boy in for a wedding reception?

[YellowFeathers]

Don't know if this should be in style either.

BIL and his lady are getting married abroad on Xmas eve but are having a reception when they get back.

Thing is what do I dress my new little baby in. If he was a she then I wouldn't think twice about it but it seems silly buying a little suit for an almost 5 month old. It must feel quite restricting for them but at the same time I don't want to stick him in a sleepsuit lol.

I've seen a lovely beige linen suit in Monsoon but I don't think I'll get something like that at that time of year.

Does anyone have any suggestions and places where to buy?

TIA

Yes thats nice SS.

and yes unborn child.

Monsoon linen jacket for a formal touch to keep SIL happy, teamed with smartish shorts/trousers from somewhere cheaper?

This is has been ds's 'posh' outfit (ie. 4 or 5 weddings/various grandparents' birthday dinners) ever since I bought the jacket in a moment of extravagance (& am consequently determined to get every possible wear out of it!). Ds's is the beige one, but they also do dark blue which might be better for winter. Not as uncomfortable looking as a suit but does look a bit 'dressed up'?