advice on what to wear as matron of honour/bridesmaid

[saffronwblue]

In a few months my dear cousin is marrying her (female) partner. I am very honoured to be asked to be bridesmaid- as we are all in our 50s it may be more a matron of honour. My cousin has told me to wear whatever I like, which is what she did as my bridesmaid 18 years ago.
Both brides are planning very elegant silk outfits - Nehru jackets from www.shibumistyle.com/en/
I want to wear something which does not clash- one bride is in hot pink, the other in turquoise. I want to look nice (obviously) and am thinking of a dress. Would navy go with the brides' colours? What would look nice on my apple shape size 18 body? The wedding is in NZ in spring so may be quite cool. I have started looking and have landed in mother of the bride territory. Budget around (150 sterling) $300.
Any suggestions on colour and or style gratefully received.

Bump?

Oh, those jackets are rather splendid.

Would it not be possible for you to pick something simpler from the same designer? Or even one of the shawls to wear with a plain dress.

I think navy would be gorgeous with hot pink and turquoise. Or maybe a darkish cream? Very sweet of them to tell you to wear whatever you like but also feels like a massive responsibility!

Navy would look good with their colours - do you normally wear dresses? A shift dress and devore jackety thing might work on you

If theres a big department store you can get to, then look to see if they have a personal shopper service. They are great for trying different things on that you might not have considered otherwise

Do you like anything here?:

m.johnlewis.com/mt/www.johnlewis.com/browse/gifts/wedding/wedding-clothing/mother-of-the-bride/_/N-5pne#page_loaded

I quite like this one but fear I will look like an old lady who is tubeshaped.
m.johnlewis.com/mt/www.johnlewis.com/gina-bacconi-fine-cornelli-floral-net-jacket/p2529540?colour=Navy&un_jtt_v_pdp=yes&un_jtt_v_from_product=un_product_18#page_loaded

What is good for apple shaped? The brides are going to be so smart and tailored I don't want to look like a frump. I think they would be a bit disconcerted if I ordered something from the same place as them, as it is a special thing they are doing together IYSWIM.